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diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/abs/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/abs/index.html new file mode 100644 index 0000000000..13f5f96b79 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/abs/index.html @@ -0,0 +1,125 @@ +--- +title: Math.abs() +slug: Web/JavaScript/Reference/Global_Objects/Math/abs +translation_of: Web/JavaScript/Reference/Global_Objects/Math/abs +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<p><code><strong>Math.abs(x)</strong></code> 函数返回指定数字 “x“ 的绝对值。如下：</p> + +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.abs</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mrow><mo stretchy="false">|</mo><mi>x</mi><mo stretchy="false">|</mo></mrow><mo>=</mo><mrow><mo>{</mo><mtable columnalign="left left"><mtr><mtd><mi>x</mi></mtd><mtd><mtext>if</mtext><mspace width="1em"></mspace><mi>x</mi><mo>≥</mo><mn>0</mn></mtd></mtr><mtr><mtd><mo>-</mo><mi>x</mi></mtd><mtd><mtext>if</mtext><mspace width="1em"></mspace><mi>x</mi><mo><</mo><mn>0</mn></mtd></mtr></mtable></mrow></mrow><annotation encoding="TeX">{\mathtt{\operatorname{Math.abs}(x)}} = {|x|} = \begin{cases} x & \text{if} \quad x \geq 0 \\ -x & \text{if} \quad x < 0 \end{cases} </annotation></semantics></math></p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox">Math.abs(<em>x</em>);</pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值</dd> +</dl> + +<h2 id="Description" name="Description">说明</h2> + +<p><code><font face="Open Sans, sans-serif"><span style="line-height: 21px;">由于 </span></font>Math.abs()</code> <code>是</code> <code>Math</code> 中的一个静态方法，你应该通过 <code>Math.abs()</code> <code>调用。</code>（Math 不是构造器）</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example:_Math.abs_behavior" name="Example:_Math.abs_behavior"><code>Math.abs()函数的行为</code></h3> + +<p>传入一个非数字形式的字符串或者 undefined/empty 变量，将返回 <code>NaN</code>。传入 null 将返回 0。</p> + +<pre class="brush:js">Math.abs('-1'); // 1 +Math.abs(-2); // 2 +Math.abs(null); // 0 +Math.abs("string"); // NaN +Math.abs(); // NaN</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.1', 'Math.abs')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.abs', 'Math.abs')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.ceil()")}}</li> + <li>{{jsxref("Math.floor()")}}</li> + <li>{{jsxref("Math.round()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/acos/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/acos/index.html new file mode 100644 index 0000000000..7ff574d177 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/acos/index.html @@ -0,0 +1,115 @@ +--- +title: Math.acos() +slug: Web/JavaScript/Reference/Global_Objects/Math/acos +translation_of: Web/JavaScript/Reference/Global_Objects/Math/acos +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.acos()</strong></code> 返回一个数的反余弦值（单位为弧度），即：</p> +<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>∊</mo><mo stretchy="false">[</mo><mrow><mo>-</mo><mn>1</mn></mrow><mo>;</mo><mn>1</mn><mo stretchy="false">]</mo><mo>,</mo><mspace width="thickmathspace"></mspace><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.acos</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">arccos</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>∊</mo><mo stretchy="false">[</mo><mn>0</mn><mo>;</mo><mi>π</mi><mo stretchy="false">]</mo><mspace width="thinmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">cos</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \in [{-1};1],\;\mathtt{\operatorname{Math.acos}(x)} = \arccos(x) = \text{ the unique } \; y \in [0; \pi] \, \text{such that} \; \cos(y) = x</annotation></semantics></math></p> +<h2 id="Syntax" name="Syntax">语法</h2> +<pre class="syntaxbox">Math.acos(<em>x</em>) </pre> +<h2 id="Parameters" name="Parameters">参数</h2> +<dl> + <dt> + <code>x</code></dt> + <dd> + 一个数值</dd> +</dl> +<h2 id="Description" name="Description">描述</h2> +<p><code>acos</code> 方法以 -1 到 1 的一个数为参数，返回一个 0 到 pi （弧度）的数值。如果传入的参数值超出了限定的范围，将返回 <code>NaN</code>。</p> +<p>由于 <code>acos</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.acos()</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是一个构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.acos" name="Example:_Using_Math.acos">例子：使用 <code>Math.acos</code></h3> +<pre class="brush:js">Math.acos(-2); // NaN +Math.acos(-1); // 3.141592653589793 +Math.acos(0); // 1.5707963267948966 +Math.acos(0.5); // 1.0471975511965979 +Math.acos(1); // 0 +Math.acos(2); // NaN +</pre> +<p>对于小于 -1 或大于 1 的值，<code>Math.acos</code> 返回 <code>NaN</code>。</p> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.2', 'Math.acos')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.acos', 'Math.acos')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.asin()")}}</li> + <li>{{jsxref("Math.atan()")}}</li> + <li>{{jsxref("Math.atan2()")}}</li> + <li>{{jsxref("Math.cos()")}}</li> + <li>{{jsxref("Math.sin()")}}</li> + <li>{{jsxref("Math.tan()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/asin/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/asin/index.html new file mode 100644 index 0000000000..de7ebe61b3 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/asin/index.html @@ -0,0 +1,114 @@ +--- +title: Math.asin() +slug: Web/JavaScript/Reference/Global_Objects/Math/asin +translation_of: Web/JavaScript/Reference/Global_Objects/Math/asin +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.asin()</strong></code> 方法返回一个数值的反正弦（单位为弧度），即：</p> +<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>∊</mo><mo stretchy="false">[</mo><mrow><mo>-</mo><mn>1</mn></mrow><mo>;</mo><mn>1</mn><mo stretchy="false">]</mo><mo>,</mo><mspace width="thickmathspace"></mspace><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.asin</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">arcsin</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>∊</mo><mrow><mo>[</mo><mrow><mo>-</mo><mfrac><mi>π</mi><mn>2</mn></mfrac><mo>;</mo><mfrac><mi>π</mi><mn>2</mn></mfrac></mrow><mo>]</mo></mrow><mspace width="thinmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">sin</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \in [{-1};1],\;\mathtt{\operatorname{Math.asin}(x)} = \arcsin(x) = \text{ the unique } \; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] \, \text{such that} \; \sin(y) = x</annotation></semantics></math></p> +<h2 id="Syntax" name="Syntax">语法</h2> +<pre class="syntaxbox">Math.asin(<em>x</em>)</pre> +<h3 id="Parameters" name="Parameters">参数</h3> +<dl> + <dt> + <code>x</code></dt> + <dd> + 一个数值</dd> +</dl> +<h2 id="Description" name="Description">描述</h2> +<p><code>asin</code> 方法接受 -1 到 1 之间的数值作为参数，返回一个介于 <math><semantics><mrow><mo>-</mo><mfrac><mi>π</mi><mn>2</mn></mfrac></mrow><annotation encoding="TeX">-\frac{\pi}{2}</annotation></semantics></math> 到 <math><semantics><mfrac><mi>π</mi><mn>2</mn></mfrac><annotation encoding="TeX">\frac{\pi}{2}</annotation></semantics></math> 弧度的数值。如果接受的参数值超出范围，则返回 <code>NaN</code>。</p> +<p>由于 <code>asin</code> 是 <code>Math</code> 的静态方法，所有应该像这样使用：<code>Math.asin()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.asin" name="Example:_Using_Math.asin">例子：使用 <code>Math.asin()</code></h3> +<pre class="brush:js">Math.asin(-2); // NaN +Math.asin(-1); // -1.5707963267948966 (-pi/2) +Math.asin(0); // 0 +Math.asin(0.5); // 0.5235987755982989 +Math.asin(1); // 1.570796326794897 (pi/2) +Math.asin(2); // NaN</pre> +<p>对于小于 -1 或大于 1 的参数值，<code>Math.asin</code> 返回 <code>NaN</code>。</p> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.3', 'Math.asin')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.asin', 'Math.asin')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.acos()")}}</li> + <li>{{jsxref("Math.atan()")}}</li> + <li>{{jsxref("Math.atan2()")}}</li> + <li>{{jsxref("Math.cos()")}}</li> + <li>{{jsxref("Math.sin()")}}</li> + <li>{{jsxref("Math.tan()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/asinh/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/asinh/index.html new file mode 100644 index 0000000000..2d7afa3b8f --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/asinh/index.html @@ -0,0 +1,87 @@ +--- +title: Math.asinh() +slug: Web/JavaScript/Reference/Global_Objects/Math/asinh +translation_of: Web/JavaScript/Reference/Global_Objects/Math/asinh +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.asinh()</code></strong> 返回一个数值的反双曲正弦值，即：</p> + +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.asinh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="thinmathspace">arsinh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">sinh</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\mathtt{\operatorname{Math.asinh}(x)} = \operatorname{arsinh}(x) = \text{ the unique } \; y \; \text{such that} \; \sinh(y) = x</annotation></semantics></math></p> + +<div>{{EmbedInteractiveExample("pages/js/math-asinh.html")}}</div> + + + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>Math.asinh(<var>x</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值.</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>返回指定数值的反双曲正弦值.</p> + +<h2 id="描述">描述</h2> + +<p>由于 <code>asinh()</code> 是 <code>Math 的静态方法</code>,所以应该像这样使用：<code>Math.asinh()</code>，而不是作为你创建的 <code>Math</code> 实例的方法（<code>Math 不是一个构造函数</code>）。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Math.asinh"> 使用 <code>Math.asinh()</code></h3> + +<pre class="brush: js">Math.asinh(1); // 0.881373587019543 +Math.asinh(0); // 0 +</pre> + +<h2 id="Polyfill">Polyfill</h2> + +<p>As a quick and dirty hack the expression <math><semantics><mrow><mo lspace="0em" rspace="thinmathspace">arsinh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mo lspace="0em" rspace="0em">ln</mo><mrow><mo>(</mo><mrow><mi>x</mi><mo>+</mo><msqrt><mrow><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>1</mn></mrow></msqrt></mrow><mo>)</mo></mrow></mrow><annotation encoding="TeX">\operatorname {arsinh} (x) = \ln \left(x + \sqrt{x^{2} + 1} \right)</annotation></semantics></math> may be used directly for a coarse emulation by the following function:</p> + +<pre class="brush: js">Math.asinh = Math.asinh || function(x) { + if (x === -Infinity) { + return x; + } else { + return Math.log(x + Math.sqrt(x * x + 1)); + } +}; +</pre> + +<p>Been formally correct it suffers from a number of issues related to floating point computations. Accurate result requires special handling of positive/negative, small/large arguments as it done e.g. in <a href="https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/ieee754/dbl-64/s_asinh.c">glibc</a> or <a href="http://git.savannah.gnu.org/cgit/gsl.git/tree/sys/invhyp.c">GNU Scientific Library</a>.</p> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <thead> + <tr> + <th scope="col">Specification</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.asinh', 'Math.asinh')}}</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> + +<p>{{Compat("javascript.builtins.Math.asinh")}}</p> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Math.acosh()")}}</li> + <li>{{jsxref("Math.atanh()")}}</li> + <li>{{jsxref("Math.cosh()")}}</li> + <li>{{jsxref("Math.sinh()")}}</li> + <li>{{jsxref("Math.tanh()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/atan/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/atan/index.html new file mode 100644 index 0000000000..cd10d30644 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/atan/index.html @@ -0,0 +1,110 @@ +--- +title: Math.atan() +slug: Web/JavaScript/Reference/Global_Objects/Math/atan +translation_of: Web/JavaScript/Reference/Global_Objects/Math/atan +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.atan()</strong></code> 函数返回一个数值的反正切（以弧度为单位），即：</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.atan</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">arctan</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>∊</mo><mrow><mo>[</mo><mrow><mo>-</mo><mfrac><mi>π</mi><mn>2</mn></mfrac><mo>;</mo><mfrac><mi>π</mi><mn>2</mn></mfrac></mrow><mo>]</mo></mrow><mspace width="thinmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">tan</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\mathtt{\operatorname{Math.atan}(x)} = \arctan(x) = \text{ the unique } \; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] \, \text{such that} \; \tan(y) = x</annotation></semantics></math></p> +<h2 id="Syntax" name="Syntax">语法</h2> +<pre class="syntaxbox">Math.atan(<em>x</em>)</pre> +<h3 id="Parameters" name="Parameters">参数</h3> +<dl> + <dt> + <code>x</code></dt> + <dd> + 一个数值</dd> +</dl> +<h2 id="Description" name="Description">描述</h2> +<p><code>atan</code> 返回一个 <math><semantics><mrow><mo>-</mo><mfrac><mi>π</mi><mn>2</mn></mfrac></mrow><annotation encoding="TeX">-\frac{\pi}{2}</annotation></semantics></math> 到 <math><semantics><mfrac><mi>π</mi><mn>2</mn></mfrac><annotation encoding="TeX">\frac{\pi}{2}</annotation></semantics></math> 弧度之间的数值。</p> +<p>由于 <code>atan</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.atan()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.atan" name="Example:_Using_Math.atan">例子：使用 <code>Math.atan</code></h3> +<pre class="brush:js">Math.atan(1); // 0.7853981633974483 +Math.atan(0); // 0 +</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.4', 'Math.atan')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.atan', 'Math.atan')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.acos()")}}</li> + <li>{{jsxref("Math.asin()")}}</li> + <li>{{jsxref("Math.atan2()")}}</li> + <li>{{jsxref("Math.cos()")}}</li> + <li>{{jsxref("Math.sin()")}}</li> + <li>{{jsxref("Math.tan()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/atan2/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/atan2/index.html new file mode 100644 index 0000000000..7bf921655d --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/atan2/index.html @@ -0,0 +1,140 @@ +--- +title: Math.atan2() +slug: Web/JavaScript/Reference/Global_Objects/Math/atan2 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/atan2 +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.atan2(</strong></code><code><strong>)</strong></code> 返回从原点(0,0)到(x,y)点的线段与x轴正方向之间的平面角度(弧度值)，也就是Math.atan2(y,x)</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox">Math.atan2(<em>y</em>, <em>x</em>) </pre> + +<h2 id="Parameters" name="Parameters">参数</h2> + +<dl> + <dt><code>y, x</code></dt> + <dd>数值</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p><code>atan2</code> 方法返回一个 -pi 到 pi 之间的数值，表示点 (x, y) 对应的偏移角度。这是一个逆时针角度，以弧度为单位，正X轴和点 (x, y) 与原点连线 之间。注意此函数接受的参数：先传递 y 坐标，然后是 x 坐标。</p> + +<p><code>atan2</code> 接受单独的 x 和 y 参数，而 <code>atan</code> 接受两个参数的比值。</p> + +<p>由于 <code>atan2</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.atan2()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example_Using_Math.atan2" name="Example:_Using_Math.atan2">例子：使用 <code>Math.atan2</code></h3> + +<pre class="brush:js">Math.atan2(90, 15) // 1.4056476493802699 +Math.atan2(15, 90) // 0.16514867741462683 + +<code>Math.atan2( ±0, -0 )</code> // <code>±PI</code>. +<code>Math.atan2( ±0, +0 )</code> // <code>±0</code>. +<code>Math.atan2( ±0, -x )</code> // <code>±PI</code> for x > 0. +<code>Math.atan2( ±0, x )</code> // <code>±0</code> for x > 0. +<code>Math.atan2( </code><code>-y, ±0 )</code> // -<code>PI/2</code> for y > 0. +<code>Math.atan2( </code><code>y, ±0 )</code> // <code>PI/2</code> for y > 0. +<code>Math.atan2( ±y, -Infinity )</code> // <code>±PI</code> for finite y > 0. +<code>Math.atan2( ±y, +Infinity )</code> // <code>±0</code> for finite y > 0. +<code>Math.atan2( ±Infinity, x )</code> // <code>±PI/2</code> for finite x. +<code>Math.atan2( ±Infinity, -Infinity )</code> // <code>±3*PI/4</code>. +<code>Math.atan2( ±Infinity, +Infinity )</code> // <code>±PI/4</code>. +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.5', 'Math.atan2')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.atan2', 'Math.atan2')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.acos()")}}</li> + <li>{{jsxref("Math.asin()")}}</li> + <li>{{jsxref("Math.atan()")}}</li> + <li>{{jsxref("Math.cos()")}}</li> + <li>{{jsxref("Math.sin()")}}</li> + <li>{{jsxref("Math.tan()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/atanh/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/atanh/index.html new file mode 100644 index 0000000000..08af33d242 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/atanh/index.html @@ -0,0 +1,132 @@ +--- +title: Math.atanh() +slug: Web/JavaScript/Reference/Global_Objects/Math/atanh +translation_of: Web/JavaScript/Reference/Global_Objects/Math/atanh +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.atanh()</code></strong> 函数返回一个数值反双曲正切值, 即：</p> + +<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>∊</mo><mrow><mo>(</mo><mrow><mo>-</mo><mn>1</mn><mo>,</mo><mn>1</mn></mrow><mo>)</mo></mrow><mo>,</mo><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.atanh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="thinmathspace">arctanh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">tanh</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \in \left( -1, 1 \right), \mathtt{\operatorname{Math.atanh}(x)} = \operatorname{arctanh}(x) = \text{ the unique } \; y \; \text{such that} \; \tanh(y) = x</annotation></semantics></math></p> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>Math.atanh(<var>x</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值</dd> +</dl> + +<h2 id="描述">描述</h2> + +<p>由于 <code>atanh()</code> 是 <code>Math 的静态方法</code>,所以应该像这样使用：<code>Math.atanh()</code>，而不是作为你创建的 <code>Math</code> 实例的方法（<code>Math 不是一个构造函数</code>）。 </p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Math.atanh()"><code>使用 Math.atanh()</code></h3> + +<pre class="brush: js">Math.atanh(-2); // NaN +Math.atanh(-1); // -Infinity +Math.atanh(0); // 0 +Math.atanh(0.5); // 0.5493061443340548 +Math.atanh(1); // Infinity +Math.atanh(2); // NaN +</pre> + +<p>对于大于1或是小于－1的值，函数返回 {{jsxref("NaN")}} 。</p> + +<h2 id="Polyfill">Polyfill</h2> + +<p>For \left|x\right| < 1, we have \operatorname {artanh} (x) = \frac{1}{2}\ln \left( \frac{1 + x}{1 - x} \right) so this can be emulated by the following function:</p> + +<pre class="brush: js">Math.atanh = Math.atanh || function(x) { + return Math.log((1+x)/(1-x)) / 2; +}; +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.atanh', 'Math.atanh')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.atanh', 'Math.atanh')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<div>{{CompatibilityTable}}</div> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatChrome("38")}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatOpera("25")}}</td> + <td>{{CompatSafari("7.1")}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>8</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Math.acosh()")}}</li> + <li>{{jsxref("Math.asinh()")}}</li> + <li>{{jsxref("Math.cosh()")}}</li> + <li>{{jsxref("Math.sinh()")}}</li> + <li>{{jsxref("Math.tanh()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/cbrt/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/cbrt/index.html new file mode 100644 index 0000000000..d583caf717 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/cbrt/index.html @@ -0,0 +1,140 @@ +--- +title: Math.cbrt() +slug: Web/JavaScript/Reference/Global_Objects/Math/cbrt +translation_of: Web/JavaScript/Reference/Global_Objects/Math/cbrt +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.cbrt()</strong></code> 函数返回任意数字的立方根.</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox">Math.cbrt(<em>x</em>)</pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字.</dd> +</dl> + +<h3 id="返回值">返回值</h3> + + + +<p>给定数字的立方根</p> + + + +<h2 id="Description" name="Description">描述</h2> + +<p>该方法为Math的静态方法,因此请直接通过Math.cbrt()方式调用.</p> + +<p>而不是作为您创建的Math对象的方法(Math不是构造函数)。</p> + +<p><span style="font-family: 'Courier New','Andale Mono',monospace; font-weight: inherit; line-height: normal;">cbrt 是 "cube root" 的缩写, 意思是立方根.</span></p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="使用_Math.cbrt">使用 Math.cbrt()</h3> + +<pre class="brush: js">Math.cbrt(NaN); // NaN +Math.cbrt(-1); // -1 +Math.cbrt(-0); // -0 +Math.cbrt(-Infinity); // -Infinity +Math.cbrt(0); // 0 +Math.cbrt(1); // 1 +Math.cbrt(Infinity); // Infinity +Math.cbrt(null); // 0 +Math.cbrt(2); // 1.2599210498948734</pre> + +<h2 id="Polyfill"><font face="consolas, Liberation Mono, courier, monospace"><span style="background-color: rgba(220, 220, 220, 0.5);">Polyfill</span></font></h2> + +<p>为了与旧版浏览器兼容, 可使用下方函数模拟cbrt():</p> + +<pre class="brush: js" dir="rtl">if (!Math.cbrt) { + Math.cbrt = function(x) { + var y = Math.pow(Math.abs(x), 1/3); + return x < 0 ? -y : y; + }; +}</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.cbrt', 'Math.cbrt')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + + + +<h2 id="另请参见">另请参见</h2> + +<ul> + <li>{{jsxref("Math.pow()")}}</li> + <li>{{jsxref("Math.sqrt()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/ceil/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/ceil/index.html new file mode 100644 index 0000000000..9b316f075a --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/ceil/index.html @@ -0,0 +1,164 @@ +--- +title: Math.ceil() +slug: Web/JavaScript/Reference/Global_Objects/Math/ceil +tags: + - JavaScript + - Math + - 参考 + - 数学 + - 方法 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/ceil +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.ceil()</code></strong> 函数返回大于或等于一个给定数字的最小整数。</p> + +<p><strong>Note: </strong><code>Math.ceil({{jsxref("null")}})</code> returns integer 0 and does not give a {{jsxref("NaN")}} error.</p> + +<div>{{EmbedInteractiveExample("pages/js/math-ceil.html")}}</div> + + + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>Math.ceil(<var>x</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值。</dd> + <dt> + <h3 id="返回值">返回值</h3> + + <p>大于或等于给定数字的最小整数。</p> + </dt> +</dl> + +<h2 id="描述">描述</h2> + +<p>由于 <code>ceil</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.ceil()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Math.ceil">使用 <code>Math.ceil</code></h3> + +<p>下例展示了 <code>Math.ceil()</code> 的使用：</p> + +<pre class="brush: js">// Closure +(function() { + /** + * Decimal adjustment of a number. + * + * @param {String} type The type of adjustment. + * @param {Number} value The number. + * @param {Integer} exp The exponent (the 10 logarithm of the adjustment base). + * @returns {Number} The adjusted value. + */ + function decimalAdjust(type, value, exp) { + // If the exp is undefined or zero... + if (typeof exp === 'undefined' || +exp === 0) { + return Math[type](value); + } + value = +value; + exp = +exp; + // If the value is not a number or the exp is not an integer... + if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) { + return NaN; + } + // Shift + value = value.toString().split('e'); + value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp))); + // Shift back + value = value.toString().split('e'); + return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp)); + } + + // Decimal round + if (!Math.round10) { + Math.round10 = function(value, exp) { + return decimalAdjust('round', value, exp); + }; + } + // Decimal floor + if (!Math.floor10) { + Math.floor10 = function(value, exp) { + return decimalAdjust('floor', value, exp); + }; + } + // Decimal ceil + if (!Math.ceil10) { + Math.ceil10 = function(value, exp) { + return decimalAdjust('ceil', value, exp); + }; + } +})(); + +// Round +Math.round10(55.55, -1); // 55.6 +Math.round10(55.549, -1); // 55.5 +Math.round10(55, 1); // 60 +Math.round10(54.9, 1); // 50 +Math.round10(-55.55, -1); // -55.5 +Math.round10(-55.551, -1); // -55.6 +Math.round10(-55, 1); // -50 +Math.round10(-55.1, 1); // -60 +// Floor +Math.floor10(55.59, -1); // 55.5 +Math.floor10(59, 1); // 50 +Math.floor10(-55.51, -1); // -55.6 +Math.floor10(-51, 1); // -60 +// Ceil +Math.ceil10(55.51, -1); // 55.6 +Math.ceil10(51, 1); // 60 +Math.ceil10(-55.59, -1); // -55.5 +Math.ceil10(-59, 1); // -50 +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>{{SpecName('ES1')}}</td> + <td>{{Spec2('ES1')}}</td> + <td>Initial definition. Implemented in JavaScript 1.0.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.6', 'Math.ceil')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.ceil', 'Math.ceil')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.ceil', 'Math.ceil')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> + +<p>{{Compat("javascript.builtins.Math.ceil")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>{{jsxref("Math.abs()")}}</li> + <li>{{jsxref("Math.floor()")}}</li> + <li>{{jsxref("Math.round()")}}</li> + <li>{{jsxref("Math.sign()")}}</li> + <li>{{jsxref("Math.trunc()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/clz32/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/clz32/index.html new file mode 100644 index 0000000000..76501c5be5 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/clz32/index.html @@ -0,0 +1,169 @@ +--- +title: Math.clz32() +slug: Web/JavaScript/Reference/Global_Objects/Math/clz32 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/clz32 +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.clz32() </strong></code>函数返回一个数字在转换成 32 无符号整形数字的二进制形式后, 开头的 0 的个数, 比如 <code>1000000</code> 转换成 32 位无符号整形数字的二进制形式后是 <code>00000000000011110100001001000000</code>, 开头的 0 的个数是 12 个, 则 <code>Math.clz32(1000000)</code> 返回 <code>12</code>.</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.clz32 (x) +</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt>x</dt> + <dd>一个数字.</dd> +</dl> + +<h2 id="描述" style="line-height: 30px;">描述</h2> + +<p>"clz32" 是 CountLeadingZeroes32 的缩写.</p> + +<p>如果 <code>x</code> 不是数字类型, 则它首先会被转换成数字类型, 然后再转成 32 位无符号整形数字. </p> + +<p>如果转换后的 32 位无符号整形数字是 <code>0</code>, 则返回 <code>32</code>, 因为此时所有位上都是 <code>0</code>.</p> + +<p><code>NaN</code>, <code>Infinity</code>,<code> -Infinity</code> 这三个数字转成 32 位无符号整形数字后都是 <code>0</code>.</p> + +<p><span>这个函数主要用于那些编译目标为 JS 语言的系统中, 比如 Emscripten.</span></p> + +<h2 id="示例">示例</h2> + +<pre class="brush: js">Math.clz32(1) // 31 +Math.clz32(1000) // 22 +Math.clz32() // 32 +[NaN, Infinity, -Infinity, 0, -0, null, undefined, "foo", {}, []].filter(function (n) { + return Math.clz32(n) !== 32 +}) // [] +Math.clz32(true) // 31 +Math.clz32(3.5) // 30 +</pre> + +<h2 id="Compatibility" name="Compatibility">计算前导1的个数</h2> + +<p>目前javascript尚未提供<code>Math.clon</code>函数来计算前导1的个数（之所以叫“clon”而非“clo”，是因为“clo”与“clz”太过相似，特别对那些母语不是英语的人来说），但是你可以通过将一个数取反并将其作为<code>Math.clz32</code>的参数来实现clon函数。其中的原理非常简单，因为对1取反是0，反之亦然，所以用<code>Math.clz32</code>计算前导0的个数就变成计算前导1的个数。</p> + +<p>先看以下代码：</p> + +<pre>var a = 32776; // 00000000000000001000000000001000 (16个前导0) +Math.clz32(a); // 16 + +var b = ~32776; // 11111111111111110111111111110111 (对32776取反, 0个前导0) +Math.clz32(b); // 0 (相当于0个前导1)</pre> + +<p>通过以上方法，<code>clon</code> 函数可以定义如下：</p> + +<pre>var clz = Math.clz32; +function clon(integer){ + return clz(~integer); +}</pre> + +<p>现在，我们可以进一步实现计算“尾随0”和“尾随1”的个数了。下面的<code>ctrz</code>函数将第一个1之后的高数位全部置为1然后取反，再用<code>Math.clz32求得</code>尾随0的个数。</p> + +<pre>var clz = Math.clz32; +function ctrz(integer){ // 计算尾随0个数 + // 1. 将第一个1之后的高数位全部置为1 + // 00000000000000001000000000001000 => 11111111111111111111111111111000 + integer |= integer << 16; + integer |= integer << 8; + integer |= integer << 4; + integer |= integer << 2; + integer |= integer << 1; + // 2. 然后，对该数取反，此时低位的1的个数即为所求 + return 32 - clz(~integer) |0; // `|0`用于保证结果为整数 +} +function ctron(integer){ // 计算尾随1个数 + // JavaScript中没有移位补1的运算符 + // 所以下面的代码是最快的 + return ctrz(~integer); + /* 为了看起来比较对称，你也可以使用以下代码： + // 1. 将第一个0之后的高数位全部置为0 + integer &= (integer << 16) | 0xffff; + integer &= (integer << 8 ) | 0x00ff; + integer &= (integer << 4 ) | 0x000f; + integer &= (integer << 2 ) | 0x0003; + integer &= (integer << 1 ) | 0x0001; + // 2. 然后，对该数取反，此时低位的0的个数即为所求 + return 32 - clon(~integer) |0; + */ +}</pre> + +<p>将以上函数改写成 ASM.JS模块——然后，你就可以去跟别人炫耀了！ASM.JS就是用来干这个的。</p> + +<pre>var countTrailsMethods = (function(stdlib, foreign, heap) { + "use asm"; + var clz = stdlib.Math.clz32; + function ctrz(integer) { // 计算尾随0个数 + integer = integer | 0; // 确保是整数 + // 1. 将第一个1之后的高数位全部置为1 + // ASMjs中不允许^=、&=、和|= + integer = integer | (integer << 16); + integer = integer | (integer << 8); + integer = integer | (integer << 4); + integer = integer | (integer << 2); + integer = integer | (integer << 1); + // 2. 然后，对该数取反，此时低位的1的个数即为所求 + return 32 - clz(~integer) |0; + } + function ctron(integer) { // 计算尾随1个数 + integer = integer | 0; // 确保是整数 + return ctrz(~integer) |0; + } + // 蛋疼的是，ASM.JS必须使用糟糕的object类型： + // unfourtunately, ASM.JS demands slow crummy objects: + return {a: ctrz, b: ctron}; +})(window, null, null); +var ctrz = countTrailsMethods.a; +var ctron = countTrailsMethods.b;</pre> + +<h2 id="Compatibility" name="Compatibility">Polyfill</h2> + +<p>这个polyfill效率最高。</p> + +<pre>if (!Math.clz32) Math.clz32 = (function(log, LN2){ + return function(x) { + var asUint = x >>> 0; // 将x转换为Uint32类型 + if (asUint === 0) { + return 32; + } + return 31 - (log(asUint) / LN2 | 0) |0; // "| 0"相当于Math.floor + }; +})(Math.log, Math.LN2);</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-Math.clz32', 'Math.clz32')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<div class="hidden"> +<p>The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> +</div> + +<p>{{Compat("javascript.builtins.Math.clz32")}}</p> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math")}}</li> + <li>{{jsxref("Math.imul")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/cos/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/cos/index.html new file mode 100644 index 0000000000..55b273cad1 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/cos/index.html @@ -0,0 +1,106 @@ +--- +title: Math.cos() +slug: Web/JavaScript/Reference/Global_Objects/Math/cos +translation_of: Web/JavaScript/Reference/Global_Objects/Math/cos +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.cos()</strong></code> 函数返回一个数值的余弦值。</p> +<h2 id="Syntax" name="Syntax">语法</h2> +<pre class="syntaxbox">Math.cos(<em>x</em>)</pre> +<h3 id="Parameters" name="Parameters">参数</h3> +<dl> + <dt> + <code>x</code></dt> + <dd> + 一个以弧度为单位的数值。</dd> +</dl> +<h2 id="Description" name="Description">描述</h2> +<p><code>cos</code> 方法返回一个 -1 到 1 之间的数值，表示角度（单位：弧度）的余弦值。</p> +<p>由于 <code>cos</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.cos()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.cos" name="Example:_Using_Math.cos">例子：使用 <code>Math.cos</code></h3> +<pre class="brush:js">Math.cos(0); // 1 +Math.cos(1); // 0.5403023058681398 + +Math.cos(Math.PI); // -1 +Math.cos(2 * Math.PI); // 1 +</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.7', 'Math.cos')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.cos', 'Math.cos')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/cosh/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/cosh/index.html new file mode 100644 index 0000000000..cd5e578571 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/cosh/index.html @@ -0,0 +1,130 @@ +--- +title: Math.cosh() +slug: Web/JavaScript/Reference/Global_Objects/Math/cosh +translation_of: Web/JavaScript/Reference/Global_Objects/Math/cosh +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.cosh()</code></strong> 函数返回数值的双曲余弦函数, 可用 {{jsxref("Math.E", "constant e", "", 1)}} 表示:</p> + +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mo lspace="0em" rspace="thinmathspace">Math.cosh(x)</mo></mstyle><mo>=</mo><mfrac><mrow><msup><mi>e</mi><mi>x</mi></msup><mo>+</mo><msup><mi>e</mi><mrow><mo>-</mo><mi>x</mi></mrow></msup></mrow><mn>2</mn></mfrac></mrow><annotation encoding="TeX">\mathtt{\operatorname{Math.cosh(x)}} = \frac{e^x + e^{-x}}{2}</annotation></semantics></math></p> + +<h2 id="Syntax">Syntax</h2> + +<pre class="syntaxbox"><code>Math.cosh(<var>x</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>数值.</dd> +</dl> + +<h2 id="描述">描述</h2> + +<p>由于<code>cosh()</code> 是Math的静态函数, 只需通过<code>Math.cosh() </code>调用,而不用通过创建Math对象来调用.</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Math.cosh()">使用 <code>Math.cosh()</code></h3> + +<pre class="brush: js">Math.cosh(0); // 1 +Math.cosh(1); // 1.5430806348152437 +Math.cosh(-1); // 1.5430806348152437 +</pre> + +<h2 id="Polyfill">Polyfill</h2> + +<p>可通过 {{jsxref("Math.exp()")}} 函数模拟实现:</p> + +<pre class="brush: js">Math.cosh = Math.cosh || function(x) { + return (Math.exp(x) + Math.exp(-x)) / 2; +} +</pre> + +<p>或只调用一次 {{jsxref("Math.exp()")}} 函数:</p> + +<pre class="brush: js">Math.cosh = Math.cosh || function(x) { + var y = Math.exp(x); + return (y + 1 / y) / 2; +}; +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.cosh', 'Math.cosh')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<div>{{CompatibilityTable}}</div> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatChrome("38")}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatOpera("25")}}</td> + <td>{{CompatSafari("7.1")}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>8</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Math.acosh()")}} {{experimental_inline}}</li> + <li>{{jsxref("Math.asinh()")}} {{experimental_inline}}</li> + <li>{{jsxref("Math.atanh()")}} {{experimental_inline}}</li> + <li>{{jsxref("Math.sinh()")}} {{experimental_inline}}</li> + <li>{{jsxref("Math.tanh()")}} {{experimental_inline}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/e/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/e/index.html new file mode 100644 index 0000000000..ffa4251bac --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/e/index.html @@ -0,0 +1,99 @@ +--- +title: Math.E +slug: Web/JavaScript/Reference/Global_Objects/Math/E +translation_of: Web/JavaScript/Reference/Global_Objects/Math/E +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.E</strong></code> 属性表示自然对数的底数（或称为基数），e，约等于 2.718。</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.E</mi></mstyle><mo>=</mo><mi>e</mi><mo>≈</mo><mn>2.718</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.E}} = e \approx 2.718</annotation></semantics></math></p> +<div> + {{js_property_attributes(0,0,0)}}</div> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>E</code> 是 <code>Math</code> 对象的静态属性，所以应该像这样使用：<code>Math.E</code>，而不是作为你创建的 <code>Math</code> 实例对象的属性（<code>Math</code> 不是构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.E" name="Example:_Using_Math.E">例子：使用 <code>Math.E</code></h3> +<p>下面的函数返回 e：</p> +<pre class="brush:js">function getNapier() { + return Math.E +} + +getNapier() // 2.718281828459045</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.1', 'Math.E')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.e', 'Math.E')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/exp/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/exp/index.html new file mode 100644 index 0000000000..6295073e83 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/exp/index.html @@ -0,0 +1,105 @@ +--- +title: Math.exp() +slug: Web/JavaScript/Reference/Global_Objects/Math/exp +translation_of: Web/JavaScript/Reference/Global_Objects/Math/exp +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.exp()</strong></code> 函数返回 <code>e<sup>x</sup></code>，<code>x</code> 表示参数，<code>e</code> 是<a href="/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Math/E">欧拉常数（Euler's constant）</a>，自然对数的底数。</p> +<h2 id="Syntax" name="Syntax">语法</h2> +<pre class="syntaxbox"><code>Math.exp(<em>x</em>)</code></pre> +<h3 id="Parameters" name="Parameters">参数</h3> +<dl> + <dt> + <code>x</code></dt> + <dd> + 一个数值</dd> +</dl> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>exp</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.exp()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.exp" name="Example:_Using_Math.exp">例子：使用 <code>Math.exp</code></h3> +<pre class="brush:js">Math.exp(-1); // 0.36787944117144233 +Math.exp(0); // 1 +Math.exp(1); // 2.718281828459045</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.8', 'Math.exp')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.exp', 'Math.exp')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.E")}}</li> + <li>{{jsxref("Math.log()")}}</li> + <li>{{jsxref("Math.pow()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/expm1/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/expm1/index.html new file mode 100644 index 0000000000..74502e9d83 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/expm1/index.html @@ -0,0 +1,119 @@ +--- +title: Math.expm1() +slug: Web/JavaScript/Reference/Global_Objects/Math/expm1 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/expm1 +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.expm1()</strong></code> 函数返回 <code>E<sup>x</sup> - 1</code>, 其中 <code>x</code> 是该函数的参数, <code>E</code> 是自然对数的底数 <code>2.718281828459045.</code></p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.expm1(<em>x</em>)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字.</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p><code><span style="color: #4d4e53; font-family: 'Open Sans',sans-serif; line-height: 21px;">参数 </span><code style="font-size: 14px; line-height: inherit; margin: 0px; padding: 0px; border: 0px; color: rgb(77, 78, 83);">x</code><span style="color: #4d4e53; font-family: 'Open Sans',sans-serif; line-height: 21px;"> 会被自动类型转换成 </span><code style="font-size: 14px; line-height: inherit; margin: 0px; padding: 0px; border: 0px; color: rgb(77, 78, 83);">number </code><span style="color: #4d4e53; font-family: 'Open Sans',sans-serif; line-height: 21px;">类型.</span></code></p> + +<p><code>expm1 是 "exponent minus 1" 的缩写.</code></p> + +<h2 id="Examples" name="Examples">示例</h2> + +<pre class="brush:js">Math.expm1(1) // 1.7182818284590453 +Math.expm1(-38) // -1 +Math.expm1("-38") // -1 +Math.expm1("foo") // NaN +</pre> + +<h2 id="Polyfill">Polyfill</h2> + +<p>因为我们已经有了 <code>Math.exp </code>函数, 所以很容易 polyfill.</p> + +<pre class="brush: js">Math.expm1 = Math.expm1 || function (x) { + return Math.exp(x) - 1 +} +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.expm1', 'Math.expm1')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Global_Objects/Math", "Math")}} 对象.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/floor/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/floor/index.html new file mode 100644 index 0000000000..f41d9aedfc --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/floor/index.html @@ -0,0 +1,222 @@ +--- +title: Math.floor() +slug: Web/JavaScript/Reference/Global_Objects/Math/floor +tags: + - Math.floor() + - 向下取整 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/floor +--- +<div>{{JSRef}}<br> + </div> + +<p><code><strong>Math.floor()</strong></code> 返回小于或等于一个给定数字的最大整数。</p> + +<div class="note"> +<p>Note: 可以理解 <code><strong>Math.floor()</strong></code>为向下取整</p> +</div> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox notranslate"><code>Math.floor(<em>x</em>) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数字。</dd> + <dt> + <h3 id="返回值">返回值 </h3> + + <p>一个表示小于或等于指定数字的最大整数的数字。</p> + </dt> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>由于 <code>floor</code> 是 <code>Math</code> 的一个静态方法，你总是应该像这样使用它 <code>Math.floor()</code>，而不是作为你创建的一个Math对象的一种方法（Math不是一个构造函数）。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example_Using_Math.floor" name="Example:_Using_Math.floor">例子：使用 <code>Math.floor</code></h3> + +<pre class="brush:js notranslate">Math.floor( 45.95); +// 45 +Math.floor( 45.05); +// 45 +Math.floor( 4 ); +// 4 +Math.floor(-45.05); +// -46 +Math.floor(-45.95); +// -46 + +</pre> + +<h3 id="Example_Decimal_adjustment" name="Example:_Decimal_adjustment">例子：十进制调整</h3> + +<pre class="brush:js notranslate">// Closure +(function(){ + + /** + * Decimal adjustment of a number. + * + * @param {String} type The type of adjustment. + * @param {Number} value The number. + * @param {Integer} exp The exponent (the 10 logarithm of the adjustment base). + * @returns {Number} The adjusted value. + */ + function decimalAdjust(type, value, exp) { + // If the exp is undefined or zero... + if (typeof exp === 'undefined' || +exp === 0) { + return Math[type](value); + } + value = +value; + exp = +exp; + // If the value is not a number or the exp is not an integer... + if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) { + return NaN; + } + // Shift + value = value.toString().split('e'); + value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp))); + // Shift back + value = value.toString().split('e'); + return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp)); + } + + // Decimal round + if (!Math.round10) { + Math.round10 = function(value, exp) { + return decimalAdjust('round', value, exp); + }; + } + // Decimal floor + if (!Math.floor10) { + Math.floor10 = function(value, exp) { + return decimalAdjust('floor', value, exp); + }; + } + // Decimal ceil + if (!Math.ceil10) { + Math.ceil10 = function(value, exp) { + return decimalAdjust('ceil', value, exp); + }; + } + +})(); + +// Round +Math.round10(55.55, -1); // 55.6 +Math.round10(55.549, -1); // 55.5 +Math.round10(55, 1); // 60 +Math.round10(54.9, 1); // 50 +Math.round10(-55.55, -1); // -55.5 +Math.round10(-55.551, -1); // -55.6 +Math.round10(-55, 1); // -50 +Math.round10(-55.1, 1); // -60 +// Floor +Math.floor10(55.59, -1); // 55.5 +Math.floor10(59, 1); // 50 +Math.floor10(-55.51, -1); // -55.6 +Math.floor10(-51, 1); // -60 +// Ceil +Math.ceil10(55.51, -1); // 55.6 +Math.ceil10(51, 1); // 60 +Math.ceil10(-55.59, -1); // -55.5 +Math.ceil10(-59, 1); // -50 +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.9', 'Math.floor')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.floor', 'Math.floor')}}<span style="display: none;"> </span></td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.floor', 'Math.floor')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.abs")}}</li> + <li>{{jsxref("Math.ceil()")}}</li> + <li>{{jsxref("Math.round()")}}</li> + <li>{{jsxref("Math.sign()")}}</li> + <li>{{jsxref("Math.trunc()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/fround/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/fround/index.html new file mode 100644 index 0000000000..022e84dbb6 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/fround/index.html @@ -0,0 +1,154 @@ +--- +title: Math.fround() +slug: Web/JavaScript/Reference/Global_Objects/Math/fround +translation_of: Web/JavaScript/Reference/Global_Objects/Math/fround +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><strong><code>Math.fround()</code></strong> 可以将任意的数字转换为离它最近的<a class="external" href="https://en.wikipedia.org/wiki/Single-precision_floating-point_format" title="link to the wikipedia page on single-precision floating-point format">单精度浮点数</a>形式的数字。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="brush: js"><code>Math.fround(<var>doubleFloat</var>)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>doubleFloat</code></dt> + <dd>一个 {{jsxref("Number")}}。若参数为非数字类型，则会被转投成数字。无法转换时，设置成{{jsxref("NaN")}}。</dd> +</dl> + +<h3 id="Parameters" name="Parameters">返回值</h3> + +<p>指定数字最接近的<a href="https://en.wikipedia.org/wiki/Single-precision_floating-point_format">32位单精度</a>浮点数表示。</p> + +<h2 id="Examples" name="Examples">描述</h2> + +<p>JavaScript 内部使用64位的双浮点数字，支持很高的精度。但是，有时你需要用32位浮点数字，比如你从一个{{jsxref("Float32Array")}} 读取值时。这时会产生混乱：检查一个64位浮点数和一个32位浮点数是否相等会失败，即使二个数字几乎一模一样。</p> + +<p>要解决这个问题，可以使用 <code>Math.fround()</code> 来将64位的浮点数转换为32位浮点数。在内部，JavaScript 继续把这个数字作为64位浮点数看待，仅仅是在尾数部分的第23位执行了“舍入到偶数”的操作，并将后续的尾数位设置为0。如果数字超出32位浮点数的范围，则返回 {{jsxref("Infinity")}} 或 <code>-Infinity</code>。</p> + +<p>因为<code>fround()</code> 是<code>Math</code> 的静态方法，你必须通过 <code>Math.fround()</code> 来使用，而不是调用你创建的<code>Math</code> 对象的一个实例方法（<code>Math</code>不是一个构造函数）。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="使用_Math.fround()">使用 Math.fround()</h3> + +<p>数字1.5可以在二进制数字系统中精确表示，32位和64位的值相同：</p> + +<pre class="brush: js">Math.fround(1.5); // 1.5 +Math.fround(1.5) === 1.5; // true</pre> + +<p>但是，数字1.337却无法在二进制数字系统中精确表示，所以32位和64位的值是不同的：</p> + +<pre class="brush: js">Math.fround(1.337); // 1.3370000123977661 +Math.fround(1.337) === 1.337; // false +</pre> + +<p>2<sup>150</sup> 超出32位浮点，所以返回<code>Infinity</code>：</p> + +<pre class="brush: js">2 ** 150; // 1.42724769270596e+45 +Math.fround(2 ** 150); // Infinity +</pre> + +<p>如果参数无法转换成数字，或者为 {{jsxref("NaN")}} （<code>NaN</code>），<code>Math.fround()</code> 会返回 <code>NaN</code>：</p> + +<pre class="brush: js">Math.fround('abc'); // NaN +Math.fround(NaN); // NaN +</pre> + +<p>在某些精度不高的场合下，可以通过将二个浮点数转换成32位浮点数进行比较，以解决64位浮点数比较结果不正确的问题：</p> + +<pre class="brush: js">0.1 + 0.2 == 0.3; //false + +function equal(v1, v2) { + return Math.fround(v1) == Math.fround(v2); +} + +equal(0.1 + 0.2, 0.3); //true +</pre> + +<h2 id="Polyfill" name="Polyfill">Polyfill</h2> + +<p>下面的函数可以模拟这个 API，前提是浏览器必须已经支持 {{jsxref("Float32Array")}}：</p> + +<pre class="brush: js">Math.fround = Math.fround || (function (array) { + return function(x) { + return array[0] = x, array[0]; + }; +})(new Float32Array(1));</pre> + +<h2 id="Specifications" name="Specifications">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范名称</th> + <th scope="col">规范状态</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.fround', 'Math.fround')}}</td> + <td>{{Spec2('ES6')}}</td> + </tr> + </tbody> +</table> + +<h2 id="Browser_compatibility" name="Browser_compatibility">浏览器兼容性</h2> + +<div>{{CompatibilityTable}}</div> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatChrome("38")}}</td> + <td>{{CompatGeckoDesktop("26")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatOpera("25")}}</td> + <td>{{CompatSafari("7.1")}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>iOS 8</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math.round()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/hypot/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/hypot/index.html new file mode 100644 index 0000000000..ab2b81bd7b --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/hypot/index.html @@ -0,0 +1,118 @@ +--- +title: Math.hypot() +slug: Web/JavaScript/Reference/Global_Objects/Math/hypot +tags: + - JavaScript + - Math + - 方法 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/hypot +--- +<div>{{JSRef}}</div> + +<p><code><strong>Math.hypot()</strong></code> 函数返回所有参数的平方和的平方根，即：</p> + +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.hypot</mo><mo stretchy="false">(</mo><msub><mi>v</mi><mn>1</mn></msub><mo>,</mo><msub><mi>v</mi><mn>2</mn></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mi>v</mi><mi>n</mi></msub><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><msqrt><mrow><munderover><mo>∑</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover><msubsup><mi>v</mi><mi>i</mi><mn>2</mn></msubsup></mrow></msqrt><mo>=</mo><msqrt><mrow><msubsup><mi>v</mi><mn>1</mn><mn>2</mn></msubsup><mo>+</mo><msubsup><mi>v</mi><mn>2</mn><mn>2</mn></msubsup><mo>+</mo><mo>…</mo><mo>+</mo><msubsup><mi>v</mi><mi>n</mi><mn>2</mn></msubsup></mrow></msqrt></mrow><annotation encoding="TeX">\mathtt{\operatorname{Math.hypot}(v_1, v_2, \dots, v_n)} = \sqrt{\sum_{i=1}^n v_i^2} = \sqrt{v_1^2 + v_2^2 + \dots + v_n^2}</annotation></semantics></math></p> + +<div>{{EmbedInteractiveExample("pages/js/math-hypot.html")}}</div> + + + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.hypot([<em>value1</em>[,<em>value2</em>, ...]]) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>value1, value2, ...</code></dt> + <dd>任意个数字。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>将所提供的参数求平方和后开平方根。如果有参数不能转换为数字，则返回 {{jsxref("NaN")}}。</p> + +<h2 id="Description" name="Description">描述</h2> + +<p>计算直角三角形的斜边，或复数的幅值时可以使用函数 <code>Math.sqrt(v1*v1 + v2*v2)</code> ，其中 v1 和 v2 是三角形的两个直角边或复数的实部和虚部。如果想计算更多维度，那么只需要在后面添加更多的数的平方就可以了，比如 <code>Math.sqrt(v1*v1 + v2*v2 + v3*v3 + v4*v4)</code>。</p> + +<p>本函数比 <code>Math.sqrt()</code> 更简单也更快，你只需要调用 <code>Math.hypot(v1, v2)</code> 或 <code>Math.hypot(v1, v2, v3, v4, ...)</code>。</p> + +<p>它还避免了幅值过大的问题。 JS 中最大的双精度浮点数是 <code>Number.MAX_VALUE = 1.797...e+308</code>。如果你的数字比约 1e154 大，计算其平方值会返回 Infinity，使你的结果出现问题。比如，<code>Math.sqrt(1e200*1e200 + 1e200*1e200) = Infinity</code>。如果你改用 <code>hypot()</code> 函数，你可以得到正确的答案：<code>Math.hypot(1e200, 1e200) = 1.4142...e+200</code>。在数字非常小的时候同样如此，比如 <code>Math.sqrt(1e-200*1e-200 + 1e-200*1e-200) = 0</code>，但 <code>Math.hypot(1e-200, 1e-200) =</code><code>1.4142...e-200</code> 则是正确的结果。</p> + +<p>由于 <code>hypot</code> 是 <code>Math</code> 的静态方法，所以应该以 <code>Math.hypot()</code>的方式使用，而不是作为你创建的 <code>Math</code> 对象的属性（<code>Math</code> 不是一个构造函数）。</p> + +<p>如果不传入任何参数, 则返回 +0 .</p> + +<p>如果参数列表中有至少一个参数不能被转换为数字，则返回 {{jsxref("NaN")}}。</p> + +<p>如果只传入一个参数, <code>Math.hypot(x)</code> 等同于 <code>Math.abs(x)</code>.</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Using_Math.hypot">Using <code>Math.hypot()</code></h3> + +<pre class="brush: js">Math.hypot(3, 4); // 5 +Math.hypot(3, 4, 5); // 7.0710678118654755 +Math.hypot(); // 0 +Math.hypot(NaN); // NaN +Math.hypot(3, 4, 'foo'); // NaN, +'foo' => NaN +Math.hypot(3, 4, '5'); // 7.0710678118654755, +'5' => 5 +Math.hypot(-3); // 3, the same as Math.abs(-3) +</pre> + +<h2 id="向下兼容">向下兼容</h2> + +<p>此函数可以使用如下代码模拟：</p> + +<pre class="brush: js">if (!Math.hypot) Math.hypot = function() { + var y = 0, i = arguments.length; + while (i--) y += arguments[i] * arguments[i]; + return Math.sqrt(y); +}; +</pre> + +<p>另一种避免结果溢出的实现：</p> + +<pre class="brush: js">if (!Math.hypot) Math.hypot = function (x, y) { + // https://bugzilla.mozilla.org/show_bug.cgi?id=896264#c28 + var max = 0; + var s = 0; + for (var i = 0; i < arguments.length; i += 1) { + var arg = Math.abs(Number(arguments[i])); + if (arg > max) { + s *= (max / arg) * (max / arg); + max = arg; + } + s += arg === 0 && max === 0 ? 0 : (arg / max) * (arg / max); + } + return max === 1 / 0 ? 1 / 0 : max * Math.sqrt(s); +}; +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范</th> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.hypot', 'Math.hypot')}}</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> + +<p>{{Compat("javascript.builtins.Math.hypot")}}</p> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Math.abs()")}}</li> + <li>{{jsxref("Math.pow()")}}</li> + <li>{{jsxref("Math.sqrt()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/imul/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/imul/index.html new file mode 100644 index 0000000000..67da70040d --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/imul/index.html @@ -0,0 +1,141 @@ +--- +title: Math.imul() +slug: Web/JavaScript/Reference/Global_Objects/Math/imul +translation_of: Web/JavaScript/Reference/Global_Objects/Math/imul +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<div>该函数将两个参数分别转换为 32 位整数，相乘后返回 32 位结果，类似 C 语言的 32 位整数相乘。</div> + +<div> +<p>{{EmbedInteractiveExample("pages/js/math-imul.html")}}</p> +</div> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>var<em> product</em> = Math.imul(a, b)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>a</code></dt> + <dd>被乘数.</dd> + <dt><code>b</code></dt> + <dd>乘数.</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>类似 C 语言 32 位整数相乘的结果。</p> + +<h2 id="描述">描述</h2> + +<p><code>Math.imul()</code> 可以进行类似 C 语言的 32 位整数相乘。该特性对于一些项目比如 <a href="http://en.wikipedia.org/wiki/Emscripten" title="http://en.wikipedia.org/wiki/Emscripten">Emscripten</a> 很有用。因为 <code>imul()</code> 是 <code>Math</code> 的静态方法，所以用法是 <code>Math.imul()</code>，而不是新创建的 <code>Math</code> 对象的方法(<code>Math</code> 不是构造函数)。如果使用 JavaScript 浮点数做为 <code>imul</code> 的参数，会有性能损失。这是因为相乘前 imul 会将浮点数转换为整数，相乘后会将整数重新转换为浮点数，这两步转换的开销是比较大的。imul 存在的原因是在 AsmJS(目前为止唯一一种环境)下它是快速的。AsmJS 使 JIST-optimizers 更容易实现 JavaScript 内部的整数。现代浏览器中，唯一能体现出 imul 性能优越的场景是两个 Number 内部以整数的形式相乘(仅在 AsmJS 下可行)。</p> + +<h2 id="例子">例子</h2> + +<pre class="brush: js">Math.imul(2, 4) // 8 +Math.imul(-1, 8) // -8 +Math.imul(-2, -2) // 4 +Math.imul(0xffffffff, 5) //-5 +Math.imul(0xfffffffe, 5) //-10 +</pre> + +<h2 id="Polyfill">Polyfill</h2> + +<p>下面的 JavaScript 代码可以实现该函数:</p> + +<pre class="brush: js"><span style='background-color: transparent; font-family: consolas,"Liberation Mono",courier,monospace; font-size: 1rem; font-weight: inherit; letter-spacing: -0.00278rem; white-space: pre;'>if (!Math.imul) Math.imul = function(a, b) {</span> + var aHi = (a >>> 16) & 0xffff; + var aLo = a & 0xffff; + var bHi = (b >>> 16) & 0xffff; + var bLo = b & 0xffff; + // the shift by 0 fixes the sign on the high part + // the final |0 converts the unsigned value into a signed value + return ((aLo * bLo) + (((aHi * bLo + aLo * bHi) << 16) >>> 0) | 0); +};</pre> + +<p>然而，下面的实现性能会更好一些。因为运行这段 polyfill 的浏览器很有可能会在内部使用浮点数，而不是整数表示 javascript 的 Number。</p> + +<pre class="brush: js"><span style='background-color: transparent; font-family: consolas,"Liberation Mono",courier,monospace; font-size: 1rem; font-weight: inherit; letter-spacing: -0.00278rem; white-space: pre;'>if (!Math.imul) Math.imul = function(opA, opB) {</span> + opB |= 0; // ensure that opB is an integer. opA will automatically be coerced. + // floating points give us 53 bits of precision to work with plus 1 sign bit + // automatically handled for our convienence: + // 1. 0x003fffff /*opA & 0x000fffff*/ * 0x7fffffff /*opB*/ = 0x1fffff7fc00001 + // 0x1fffff7fc00001 < Number.MAX_SAFE_INTEGER /*0x1fffffffffffff*/ + var result = (opA & 0x003fffff) * opB; + // 2. We can remove an integer coersion from the statement above because: + // 0x1fffff7fc00001 + 0xffc00000 = 0x1fffffff800001 + // 0x1fffffff800001 < Number.MAX_SAFE_INTEGER /*0x1fffffffffffff*/ + if (opA & 0xffc00000 /*!== 0*/) result += (opA & 0xffc00000) * opB |0; + return result |0; +};</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <thead> + <tr> + <th scope="col">Specification</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.imul', 'Math.imul')}}</td> + </tr> + </tbody> +</table> + + + + + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Firefox (Gecko)</th> + <th>Chrome</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatGeckoDesktop("20") }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Firefox Mobile (Gecko)</th> + <th>Android</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatGeckoMobile("20") }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + </tr> + </tbody> +</table> +</div> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/index.html new file mode 100644 index 0000000000..924ac82fc4 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/index.html @@ -0,0 +1,187 @@ +--- +title: Math +slug: Web/JavaScript/Reference/Global_Objects/Math +tags: + - JavaScript + - Math + - 参考 + - 数学 + - 计算 +translation_of: Web/JavaScript/Reference/Global_Objects/Math +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math</code></strong> 是一个内置对象，它拥有一些数学常数属性和数学函数方法。<code>Math</code> 不是一个函数对象。</p> + +<p><code>Math</code> 用于 {{jsxref("Number")}} 类型。它不支持 {{jsxref("BigInt")}}。</p> + +<h2 id="描述">描述</h2> + +<p>与其他全局对象不同的是，<code>Math</code> 不是一个构造器。<code>Math</code> 的所有属性与方法都是静态的。引用圆周率的写法是 <code>Math.PI</code>，调用正余弦函数的写法是 <code>Math.sin(x)</code>，<code>x</code> 是要传入的参数。<code>Math</code> 的常量是使用 JavaScript 中的全精度浮点数来定义的。</p> + +<h2 id="属性">属性</h2> + +<dl> + <dt>{{jsxref("Math.E")}}</dt> + <dd>欧拉常数，也是自然对数的底数，约等于 <code>2.718</code>。</dd> + <dt>{{jsxref("Math.LN2")}}</dt> + <dd><code>2</code> 的自然对数，约等于 <code>0.693</code>。</dd> + <dt>{{jsxref("Math.LN10")}}</dt> + <dd><code>10</code> 的自然对数，约等于 <code>2.303</code>。</dd> + <dt>{{jsxref("Math.LOG2E")}}</dt> + <dd>以 <code>2</code> 为底的 <code>E</code> 的对数，约等于 <code>1.443</code>。</dd> + <dt>{{jsxref("Math.LOG10E")}}</dt> + <dd>以 <code>10</code> 为底的 <code>E</code> 的对数，约等于 <code>0.434</code>。</dd> + <dt>{{jsxref("Math.PI")}}</dt> + <dd>圆周率，一个圆的周长和直径之比，约等于 <code>3.14159</code>。</dd> + <dt>{{jsxref("Math.SQRT1_2")}}</dt> + <dd>二分之一 ½ 的平方根，同时也是 <code>2</code> 的平方根的倒数 <math><mfrac><mn>1</mn><mrow><msqrt><mn>2</mn><mrow></mrow></msqrt></mrow></mfrac></math>，约等于 <code>0.707</code>。</dd> + <dt>{{jsxref("Math.SQRT2")}}</dt> + <dd><code>2</code> 的平方根，约等于 <code>1.414</code>。</dd> +</dl> + +<h2 id="方法">方法</h2> + +<div class="note"> +<p>需要注意的是，三角函数 <code>sin()</code>、<code>cos()</code>、<code>tan()</code>、<code>asin()</code>、<code>acos()</code>、<code>atan()</code> 和 <code>atan2()</code> 返回的值是<em>弧度</em>而非角度。</p> + +<p>若要转换，弧度除以 <code>(Math.PI / 180)</code> 即可转换为角度，同理，角度乘以这个数则能转换为弧度。</p> +</div> + +<div class="note"> +<p>需要注意的是，很多 <code>Math</code> 函数都有一个精度，而且这个精度在不同实现中也是不相同的。这意味着不同的浏览器会给出不同的结果，甚至，在不同的系统或架构下，相同的 JS 引擎也会给出不同的结果！</p> +</div> + +<dl> + <dt>{{jsxref("Global_Objects/Math/abs", "Math.abs(<var>x</var>)")}}</dt> + <dd>返回一个数的绝对值。</dd> + <dt>{{jsxref("Global_Objects/Math/acos", "Math.acos(<var>x</var>)")}}</dt> + <dd>返回一个数的反余弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/acosh", "Math.acosh(<var>x</var>)")}}</dt> + <dd>返回一个数的反双曲余弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/asin", "Math.asin(<var>x</var>)")}}</dt> + <dd>返回一个数的反正弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/asinh", "Math.asinh(<var>x</var>)")}}</dt> + <dd>返回一个数的反双曲正弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/atan", "Math.atan(<var>x</var>)")}}</dt> + <dd>返回一个数的反正切值。</dd> + <dt>{{jsxref("Global_Objects/Math/atanh", "Math.atanh(<var>x</var>)")}}</dt> + <dd>返回一个数的反双曲正切值。</dd> + <dt>{{jsxref("Global_Objects/Math/atan2", "Math.atan2(<var>y</var>, <var>x</var>)")}}</dt> + <dd>返回 <code>y/x</code> 的反正切值。</dd> + <dt>{{jsxref("Global_Objects/Math/cbrt", "Math.cbrt(<var>x</var>)")}}</dt> + <dd>返回一个数的立方根。</dd> + <dt>{{jsxref("Global_Objects/Math/ceil", "Math.ceil(<var>x</var>)")}}</dt> + <dd>返回大于一个数的最小整数，即一个数向上取整后的值。</dd> + <dt>{{jsxref("Global_Objects/Math/clz32", "Math.clz32(<var>x</var>)")}}</dt> + <dd>返回一个 32 位整数的前导零的数量。</dd> + <dt>{{jsxref("Global_Objects/Math/cos", "Math.cos(<var>x</var>)")}}</dt> + <dd>返回一个数的余弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/cosh", "Math.cosh(<var>x</var>)")}}</dt> + <dd>返回一个数的双曲余弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/exp", "Math.exp(<var>x</var>)")}}</dt> + <dd>返回欧拉常数的参数次方，<code>E<var><sup>x</sup></var></code>，其中 <code><var>x</var></code> 为参数，<code>E</code> 是欧拉常数（2.718...，自然对数的底数）。</dd> + <dt>{{jsxref("Global_Objects/Math/expm1", "Math.expm1(<var>x</var>)")}}</dt> + <dd>返回 <code>exp(x) - 1</code> 的值。</dd> + <dt>{{jsxref("Global_Objects/Math/floor", "Math.floor(<var>x</var>)")}}</dt> + <dd>返回小于一个数的最大整数，即一个数向下取整后的值。</dd> + <dt>{{jsxref("Global_Objects/Math/fround", "Math.fround(<var>x</var>)")}}</dt> + <dd>返回最接近一个数的<a href="https://zh.wikipedia.org/wiki/%E5%96%AE%E7%B2%BE%E5%BA%A6%E6%B5%AE%E9%BB%9E%E6%95%B8">单精度浮点型</a>表示。</dd> + <dt>{{jsxref("Global_Objects/Math/hypot", "Math.hypot([<var>x</var>[, <var>y</var>[, …]]])")}}</dt> + <dd>返回其所有参数平方和的平方根。</dd> + <dt>{{jsxref("Global_Objects/Math/imul", "Math.imul(<var>x</var>, <var>y</var>)")}}</dt> + <dd>返回 32 位整数乘法的结果。</dd> + <dt>{{jsxref("Global_Objects/Math/log", "Math.log(<var>x</var>)")}}</dt> + <dd>返回一个数的自然对数（㏒<sub>e</sub>，即 ㏑）。</dd> + <dt>{{jsxref("Global_Objects/Math/log1p", "Math.log1p(<var>x</var>)")}}</dt> + <dd>返回一个数加 1 的和的自然对数（㏒<sub>e</sub>，即 ㏑）。</dd> + <dt>{{jsxref("Global_Objects/Math/log10", "Math.log10(<var>x</var>)")}}</dt> + <dd>返回一个数以 10 为底数的对数。</dd> + <dt>{{jsxref("Global_Objects/Math/log2", "Math.log2(<var>x</var>)")}}</dt> + <dd>返回一个数以 2 为底数的对数。</dd> + <dt>{{jsxref("Global_Objects/Math/max", "Math.max([<var>x</var>[, <var>y</var>[, …]]])")}}</dt> + <dd>返回零到多个数值中最大值。</dd> + <dt>{{jsxref("Global_Objects/Math/min", "Math.min([<var>x</var>[, <var>y</var>[, …]]])")}}</dt> + <dd>返回零到多个数值中最小值。</dd> + <dt>{{jsxref("Global_Objects/Math/pow", "Math.pow(<var>x</var>, <var>y</var>)")}}</dt> + <dd>返回一个数的 y 次幂。</dd> + <dt>{{jsxref("Global_Objects/Math/random", "Math.random()")}}</dt> + <dd>返回一个 0 到 1 之间的伪随机数。</dd> + <dt>{{jsxref("Global_Objects/Math/round", "Math.round(<var>x</var>)")}}</dt> + <dd>返回四舍五入后的整数。</dd> + <dt>{{jsxref("Global_Objects/Math/sign", "Math.sign(<var>x</var>)")}}</dt> + <dd>返回一个数的符号，得知一个数是正数、负数还是 0。</dd> + <dt>{{jsxref("Global_Objects/Math/sin", "Math.sin(<var>x</var>)")}}</dt> + <dd>返回一个数的正弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/sinh", "Math.sinh(<var>x</var>)")}}</dt> + <dd>返回一个数的双曲正弦值。</dd> + <dt>{{jsxref("Global_Objects/Math/sqrt", "Math.sqrt(<var>x</var>)")}}</dt> + <dd>返回一个数的平方根。</dd> + <dt>{{jsxref("Global_Objects/Math/tan", "Math.tan(<var>x</var>)")}}</dt> + <dd>返回一个数的正切值。</dd> + <dt>{{jsxref("Global_Objects/Math/tanh", "Math.tanh(<var>x</var>)")}}</dt> + <dd>返回一个数的双曲正切值。</dd> + <dt><code>Math.toSource()</code></dt> + <dd>返回字符串 <code>"Math"</code>。</dd> + <dt>{{jsxref("Global_Objects/Math/trunc", "Math.trunc(<var>x</var>)")}}</dt> + <dd>返回一个数的整数部分，直接去除其小数点及之后的部分。</dd> +</dl> + +<div class="hidden"> +<div class="note"> +<p>已被移除的内容：</p> +</div> + +<h2 id="拓展_Math_对象">拓展 <code>Math</code> 对象</h2> + +<p>As with most of the built-in objects in JavaScript, the <code>Math</code> object can be extended with custom properties and methods. To extend the <code>Math</code> object, you do not use <code>prototype</code>. Instead, you directly extend <code>Math</code>:</p> + +<pre>Math.propName = propValue; +Math.methodName = methodRef;</pre> + +<p>For instance, the following example adds a method to the <code>Math</code> object for calculating the <em>greatest common divisor</em> of a list of arguments.</p> + +<pre class="brush: js">/* Variadic function -- Returns the greatest common divisor of a list of arguments */ +Math.gcd = function() { + if (arguments.length == 2) { + if (arguments[1] == 0) + return arguments[0]; + else + return Math.gcd(arguments[1], arguments[0] % arguments[1]); + } else if (arguments.length > 2) { + var result = Math.gcd(arguments[0], arguments[1]); + for (var i = 2; i < arguments.length; i++) + result = Math.gcd(result, arguments[i]); + return result; + } +};</pre> + +<p>试试运行下面的代码：</p> + +<pre class="brush: js">console.log(Math.gcd(20, 30, 15, 70, 40)); // `5`</pre> +</div> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范</th> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math-object', 'Math')}}</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> + +<p>{{Compat("javascript.builtins.Math")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>{{jsxref("Number")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/ln10/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/ln10/index.html new file mode 100644 index 0000000000..dac9f67466 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/ln10/index.html @@ -0,0 +1,99 @@ +--- +title: Math.LN10 +slug: Web/JavaScript/Reference/Global_Objects/Math/LN10 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/LN10 +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.LN10</strong></code> 属性表示 10 的自然对数，约为 2.302：</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.LN10</mi></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">ln</mo><mo stretchy="false">(</mo><mn>10</mn><mo stretchy="false">)</mo><mo>≈</mo><mn>2.302</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.LN10}} = \ln(10) \approx 2.302</annotation></semantics></math></p> +<div> + {{js_property_attributes(0,0,0)}}</div> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>LN10</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.LN10</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.LN10" name="Example:_Using_Math.LN10">例子：使用 <code>Math.LN10</code></h3> +<p>下面的函数返回 10 的自然对数：</p> +<pre class="brush:js">function getNatLog10() { + return Math.LN10 +} + +getNatLog10() // 2.302585092994046</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.2', 'Math.LN10')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.ln10', 'Math.LN10')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/ln2/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/ln2/index.html new file mode 100644 index 0000000000..ab79666f23 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/ln2/index.html @@ -0,0 +1,99 @@ +--- +title: Math.LN2 +slug: Web/JavaScript/Reference/Global_Objects/Math/LN2 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/LN2 +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.LN2</strong></code> 属性表示 2 的自然对数，约为 0.693：</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.LN2</mi></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">ln</mo><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo><mo>≈</mo><mn>0.693</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.LN2}} = \ln(2) \approx 0.693</annotation></semantics></math></p> +<div> + {{js_property_attributes(0,0,0)}}</div> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>LN2</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.LN2</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.LN2" name="Example:_Using_Math.LN2">例子：使用 <code>Math.LN2</code></h3> +<p>下面的函数返回 2 的自然对数：</p> +<pre class="brush:js">function getNatLog2() { + return Math.LN2 +} + +getNatLog2() // 0.6931471805599453</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.3', 'Math.LN2')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.ln2', 'Math.LN2')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/log/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/log/index.html new file mode 100644 index 0000000000..d91a937ec1 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/log/index.html @@ -0,0 +1,139 @@ +--- +title: Math.log() +slug: Web/JavaScript/Reference/Global_Objects/Math/log +translation_of: Web/JavaScript/Reference/Global_Objects/Math/log +--- +<p id="Summary">{{JSRef("Global_Objects", "Math")}}</p> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.log()</strong></code> 函数返回一个数的自然对数，即：</p> + +<p><math><semantics><mrow><mo>∀</mo><mi>x</mi><mo>></mo><mn>0</mn><mo>,</mo><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.log</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">ln</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext>the unique</mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><msup><mi>e</mi><mi>y</mi></msup><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x > 0, \mathtt{\operatorname{Math.log}(x)} = \ln(x) = \text{the unique} \; y \; \text{such that} \; e^y = x</annotation></semantics></math></p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.log(<em>x</em>)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数字.</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>如果指定的 <code>number</code> 为负数，则返回值为 <code>NaN</code>。</p> + +<p>由于 <code style="font-style: normal;">log</code> 是 <code style="font-style: normal;">Math</code> 的静态方法，所以应该像这样使用：<code style="font-style: normal;">Math.log()</code>，而不是作为你创建的 <code style="font-style: normal;">Math</code> 对象的方法。</p> + +<h2 id="示例">示例</h2> + +<h3 id="Example:_Using_Math.log" name="Example:_Using_Math.log">例子1:使用<code>Math.log</code></h3> + +<p>下面的函数返回指定变量的自然对数：</p> + +<pre class="brush:js">Math.log(-1); // NaN, out of range +Math.log(0); // -Infinity +Math.log(1); // 0 +Math.log(10); // 2.302585092994046</pre> + +<h3 id="例子2_使用Math.log时基于不同的底数">例子2: 使用<code>Math.log</code>时基于不同的底数</h3> + +<p>下面的函数返回以 <code>x</code> 为底 <code>y</code> 的对数（即log<sub>x</sub> y）：</p> + +<pre class="brush:js">function getBaseLog(x, y) { + return Math.log(y) / Math.log(x); +}</pre> + +<p>如果你运行 <code>getBaseLog(10, 1000)，则会返回</code><code>2.9999999999999996，非常接近实际答案：3，原因是浮点数精度问题。</code></p> + +<h2 id="规范" style="margin-bottom: 20px; line-height: 30px;">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.10', 'Math.log')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.log', 'Math.log')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性" style="margin-bottom: 20px; line-height: 30px;">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th style="line-height: 16px;">Feature</th> + <th style="line-height: 16px;">Chrome</th> + <th style="line-height: 16px;">Firefox (Gecko)</th> + <th style="line-height: 16px;">Internet Explorer</th> + <th style="line-height: 16px;">Opera</th> + <th style="line-height: 16px;">Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th style="line-height: 16px;">Feature</th> + <th style="line-height: 16px;">Android</th> + <th style="line-height: 16px;">Chrome for Android</th> + <th style="line-height: 16px;">Firefox Mobile (Gecko)</th> + <th style="line-height: 16px;">IE Mobile</th> + <th style="line-height: 16px;">Opera Mobile</th> + <th style="line-height: 16px;">Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also" style="margin-bottom: 20px; line-height: 30px;">相关链接</h2> + +<p></p> + +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> + <li>{{jsxref("Math.exp()")}}</li> + <li>{{jsxref("Math.pow()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/log10/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/log10/index.html new file mode 100644 index 0000000000..7819f922e8 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/log10/index.html @@ -0,0 +1,113 @@ +--- +title: Math.log10() +slug: Web/JavaScript/Reference/Global_Objects/Math/log10 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/log10 +--- +<div> +<div>{{JSRef("Global_Objects", "Math")}}</div> +</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.log10()</strong></code> 函数返回<span style="color: #4d4e53; line-height: 1.5;">一个数字以 10 为底的对数.</span></p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.log10(<em>x</em>)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字.</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>如果传入的参数小于 0, 则返回 NaN.</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<pre class="brush:js">Math.log10(10) // 1 +Math.log10(100) // 2 +Math.log10("100")// 2 +Math.log10(1) // 0 +Math.log10(0) // -Infinity +Math.log10(-2) // NaN +Math.log10("foo")// NaN +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.log10', 'Math.log10')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Global_Objects/Math", "Math")}} 对象.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/log10e/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/log10e/index.html new file mode 100644 index 0000000000..3a929935f1 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/log10e/index.html @@ -0,0 +1,99 @@ +--- +title: Math.LOG10E +slug: Web/JavaScript/Reference/Global_Objects/Math/LOG10E +translation_of: Web/JavaScript/Reference/Global_Objects/Math/LOG10E +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.LOG10E</strong></code> 属性表示以 10 为底数，e 的对数，约为 0.434：</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.LOG10E</mi></mstyle><mo>=</mo><msub><mo lspace="0em" rspace="0em">log</mo><mn>10</mn></msub><mo stretchy="false">(</mo><mi>e</mi><mo stretchy="false">)</mo><mo>≈</mo><mn>0.434</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.LOG10E}} = \log_10(e) \approx 0.434</annotation></semantics></math></p> +<div> + {{js_property_attributes(0,0,0)}}</div> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>LOG10E</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.LOG10E</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是一个构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.LOG10E" name="Example:_Using_Math.LOG10E">例子：使用 <code>Math.LOG10E</code></h3> +<p>下面的函数返回以 10为底数，E的对数：</p> +<pre class="brush:js">function getLog10e() { + return Math.LOG10E +} + +getLog10e() // 0.4342944819032518</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.5', 'Math.LOG10E')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.log10e', 'Math.LOG10E')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/log1p/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/log1p/index.html new file mode 100644 index 0000000000..2f9b0c64a5 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/log1p/index.html @@ -0,0 +1,116 @@ +--- +title: Math.log1p() +slug: Web/JavaScript/Reference/Global_Objects/Math/log1p +translation_of: Web/JavaScript/Reference/Global_Objects/Math/log1p +--- +<div> +<div>{{JSRef("Global_Objects", "Math")}}</div> +</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.log1p()</strong></code> 函数返回一个数字加1后的自然对数 (底为 <code>E</code>), 既<code>log(x+1)</code>.</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.log1p(<em>x</em>)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字.</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>如果参数的值小于<code> -1</code>, 则返回 <code>NaN.</code></p> + +<p><code>函数 y = log(x+1) 的图形是这样的:</code></p> + +<p> <img alt="log(x+1)" src="https://mdn.mozillademos.org/files/6467/logx1.jpg" style="height: 300px; width: 400px;"></p> + +<p><strong style="font-size: 30px; font-weight: 700; letter-spacing: -1px; line-height: 30px;">示例</strong></p> + +<pre class="brush:js">Math.log1p(Math.E-1) // 1 +Math.log1p(0) // 0 +Math.log1p("0") // 0 +Math.log1p(-1) // -Infinity +Math.log1p(-2) // NaN +Math.log1p("foo") // NaN +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.log1p', 'Math.log1p')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Global_Objects/Math", "Math")}} 对象.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/log2/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/log2/index.html new file mode 100644 index 0000000000..bb048cd49a --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/log2/index.html @@ -0,0 +1,113 @@ +--- +title: Math.log2() +slug: Web/JavaScript/Reference/Global_Objects/Math/log2 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/log2 +--- +<div> +<div>{{JSRef("Global_Objects", "Math")}}</div> +</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.log2()</strong></code> 函数返回一个数字以 2 为底的对数.</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.log2(<em>x</em>)</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字.</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>如果传入的参数小于 0, 则返回 <code>NaN</code>.</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<pre class="brush:js">Math.log2(2) // 1 +Math.log2(1024) // 10 +Math.log2(1) // 0 +Math.log2(0) // -Infinity +Math.log2(-2) // NaN +Math.log2("1024")// 10 +Math.log2("foo") // NaN +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.log2', 'Math.log2')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Global_Objects/Math", "Math")}} 对象.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/log2e/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/log2e/index.html new file mode 100644 index 0000000000..9c68f4cc57 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/log2e/index.html @@ -0,0 +1,99 @@ +--- +title: Math.LOG2E +slug: Web/JavaScript/Reference/Global_Objects/Math/LOG2E +translation_of: Web/JavaScript/Reference/Global_Objects/Math/LOG2E +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.LOG2E</strong></code> 属性表示以 2 为底数，e 的对数，约为 1.442：</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.LOG2E</mi></mstyle><mo>=</mo><msub><mo lspace="0em" rspace="0em">log</mo><mn>2</mn></msub><mo stretchy="false">(</mo><mi>e</mi><mo stretchy="false">)</mo><mo>≈</mo><mn>1.442</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.LOG2E}} = \log_2(e) \approx 1.442</annotation></semantics></math></p> +<div> + {{js_property_attributes(0,0,0)}}</div> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>LOG2E</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.LOG2E</code>，而不是作为你创建的 <code>Math</code> 对象的属性（<code>Math</code> 不是一个构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.LOG2E" name="Example:_Using_Math.LOG2E">例子：使用 <code>Math.LOG2E</code></h3> +<p>下面的函数返回以 2 为底数，E 的对数：</p> +<pre class="brush:js">function getLog2e() { + return Math.LOG2E +} + +getLog2e() // 1.4426950408889634</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.4', 'Math.LOG2E')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.log2e', 'Math.LOG2E')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/max/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/max/index.html new file mode 100644 index 0000000000..593776318e --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/max/index.html @@ -0,0 +1,99 @@ +--- +title: Math.max() +slug: Web/JavaScript/Reference/Global_Objects/Math/max +tags: + - JavaScript + - Math +translation_of: Web/JavaScript/Reference/Global_Objects/Math/max +--- +<div>{{JSRef}}</div> + +<p><code><strong>Math.max()</strong></code> 函数返回一组数中的最大值。</p> + +<p>{{EmbedInteractiveExample("pages/js/math-max.html")}}</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.max(<em>value1</em>[,<em>value2</em>, ...]) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>value1, value2, ...</code></dt> + <dd>一组数值</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>返回给定的一组数字中的最大值。如果给定的参数中至少有一个参数无法被转换成数字，则会返回 {{jsxref("NaN")}}。</p> + +<h2 id="Description" name="Description">描述</h2> + +<p>由于 <code>max</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.max()</code>，而不是创建的 <code>Math</code> 实例的方法（<code>Math</code> 不是构造函数）。</p> + +<p>如果没有参数，则结果为 - {{jsxref("Infinity")}}。</p> + +<p>如果有任一参数不能被转换为数值，则结果为 {{jsxref("NaN")}}。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example_Using_Math.max" name="Example:_Using_Math.max">使用 <code>Math.max()</code></h3> + +<pre>Math.max(10, 20); // 20 +Math.max(-10, -20); // -10 +Math.max(-10, 20); // 20</pre> + +<p>下面的方法使用 {{jsxref("Global_Objects/Function/apply", "apply")}} 方法寻找一个数值数组中的最大元素。<code>getMaxOfArray([1,2,3])</code> 等价于 <code>Math.max(1, 2, 3)</code>，但是你可以使用 <code>getMaxOfArray</code> ()作用于任意长度的数组上。</p> + +<pre class="brush:js">function getMaxOfArray(numArray) { + return Math.max.apply(null, numArray); +} +</pre> + +<p>或者通过使用最新的扩展语句{{jsxref("Operators/Spread_operator", "spread operator")}}，获得数组中的最大值变得更容易。</p> + +<pre class="brush: js">var arr = [1, 2, 3]; +var max = Math.max(...arr); +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>{{SpecName('ES1')}}</td> + <td>{{Spec2('ES1')}}</td> + <td>Initial definition. Implemented in JavaScript 1.0.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.11', 'Math.max')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.max', 'Math.max')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.max', 'Math.max')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{Compat("javascript.builtins.Math.max")}}</p> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math.min()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/min/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/min/index.html new file mode 100644 index 0000000000..2cc029c6c3 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/min/index.html @@ -0,0 +1,155 @@ +--- +title: Math.min() +slug: Web/JavaScript/Reference/Global_Objects/Math/min +tags: + - JavaScript + - Math + - Math.min + - 参考 + - 方法 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/min +--- +<div>{{JSRef}}</div> + +<p><code><strong>Math.min()</strong></code> 返回零个或更多个数值的最小值。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.min([<em>value1</em>[,<em>value2</em>, ...]]) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>value1, value2, ...</code></dt> + <dd>一组数值</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>给定数值中最小的数。如果任一参数不能转换为数值，则返回{{jsxref("NaN")}}。</p> + +<h2 id="Description" name="Description">描述</h2> + +<p>由于 <code>min</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.min()</code>，而不是作为你创建的 <code>Math</code> 实例的方法（Math 不是构造函数）。</p> + +<p>如果没有参数，结果为{{jsxref("Infinity")}}。</p> + +<p>如果有任一参数不能被转换为数值，结果为 {{jsxref("NaN")}}。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example:_Using_Math.min" name="Example:_Using_Math.min">使用 <code>Math.min()</code></h3> + +<p>下例找出 x 和 y 的最小值，并把它赋值给 z：</p> + +<pre class="brush:js">var x = 10, y = -20; +var z = Math.min(x, y); +</pre> + +<h3 id="Example.3A_Clipping_a_value_with_Math.min" name="Example.3A_Clipping_a_value_with_Math.min">使用 <code>Math.min()</code> 裁剪值（Clipping a value）</h3> + +<p><code>Math.min</code> 经常用于裁剪一个值，以便使其总是小于或等于某个边界值。例如：</p> + +<pre class="brush: js">var x = f(foo); + +if (x > boundary) { + x = boundary; +}</pre> + +<p>可以写成：</p> + +<pre class="brush:js">var x = Math.min(f(foo), boundary);</pre> + +<div>另外，{{jsxref("Math.max()")}} 也可以被用来以相似的方式裁剪一个值。</div> + +<div> </div> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>{{Spec2('ES1')}}</td> + <td>初始定义。在 JavaScript 1.0 中实现。</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.12', 'Math.min')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.min', 'Math.min')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.min', 'Math.min')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math.max()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html new file mode 100644 index 0000000000..77f373196e --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html @@ -0,0 +1,115 @@ +--- +title: Math.PI +slug: Web/JavaScript/Reference/Global_Objects/Math/PI +translation_of: Web/JavaScript/Reference/Global_Objects/Math/PI +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.PI</strong></code> 表示一个圆的周长与直径的比例，约为 3.14159：</p> + +<p><math><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.PI</mi></mstyle><mo>=</mo><mi>π</mi><mo>≈</mo><mn>3.14159</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.PI}} = \pi \approx 3.14159</annotation></semantics></math></p> + +<div>{{js_property_attributes(0,0,0)}}</div> + +<h2 id="Description" name="Description">描述</h2> + +<p>由于 <code>PI</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.PI</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是构造函数）。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example:_Using_PI" name="Example:_Using_PI">使用 <code>Math.PI</code></h3> + +<p>下面的函数使用 Math.PI 计算给定半径的圆周长：</p> + +<pre class="brush:js language-js" style="padding: 1em 0px 1em 30px; font-size: 14px; white-space: normal; color: rgb(77, 78, 83);"><code class="language-js" style="direction: ltr; white-space: pre;"><span class="keyword token" style="color: rgb(0, 119, 170);">function</span> calculateCircumference <span class="punctuation token" style="color: rgb(153, 153, 153);">(</span>radius<span class="punctuation token" style="color: rgb(153, 153, 153);">)</span> <span class="punctuation token" style="color: rgb(153, 153, 153);">{</span> + <span class="keyword token" style="color: rgb(0, 119, 170);">return</span> <span class="number token" style="color: rgb(153, 0, 85);">2</span> <span class="operator token" style="background: rgba(255, 255, 255, 0.498039); color: rgb(166, 127, 89);">*</span> Math<span class="punctuation token" style="color: rgb(153, 153, 153);">.</span>PI <span class="operator token" style="background: rgba(255, 255, 255, 0.498039); color: rgb(166, 127, 89);">*</span> radius<span class="punctuation token" style="color: rgb(153, 153, 153);">;</span> +<span class="punctuation token" style="color: rgb(153, 153, 153);">}</span> + +<span class="function token" style="color: rgb(221, 74, 104);">calculateCircumference<span class="punctuation token" style="color: rgb(153, 153, 153);">(</span></span><span class="number token" style="color: rgb(153, 0, 85);">1</span><span class="punctuation token" style="color: rgb(153, 153, 153);">)</span><span class="punctuation token" style="color: rgb(153, 153, 153);">;</span> <span class="comment token" style="color: rgb(112, 128, 144);"> // 6.283185307179586</span></code></pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.6', 'Math.PI')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.pi', 'Math.PI')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/pow/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/pow/index.html new file mode 100644 index 0000000000..32489252c0 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/pow/index.html @@ -0,0 +1,78 @@ +--- +title: Math.pow() +slug: Web/JavaScript/Reference/Global_Objects/Math/pow +translation_of: Web/JavaScript/Reference/Global_Objects/Math/pow +--- +<div>{{JSRef}}</div> + +<p><code><strong>Math.pow()</strong></code> 函数返回基数（<code>base</code>）的指数（<code>exponent</code>）次幂，即<span style="line-height: 1.572;"> </span><code style="font-size: 14px;">base<sup>exponent</sup></code><span style="line-height: 1.572;">。</span></p> + +<p>{{EmbedInteractiveExample("pages/js/math-pow.html")}}</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.pow(<em>base</em>, <em>exponent</em>) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>base</code></dt> + <dd>基数</dd> + <dt><code>exponent</code></dt> + <dd>指数</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>由于 <code>pow</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.pow()</code>，而不是作为你创建的 <code>Math</code> 对象的方法。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example_Using_Math.pow" name="Example:_Using_Math.pow">使用 <code>Math.pow</code></h3> + +<pre class="brush:js">function raisePower(x,y) { + return Math.pow(x,y) +}</pre> + +<p>如果 <code>x</code> 是 2 ，且 <code>y</code> 是 7，则 raisePower 函数返回 128 （2 的 7 次幂）。</p> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.13', 'Math.pow')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.pow', 'Math.pow')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{Compat("javascript.builtins.Math.pow")}}</p> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math.cbrt()")}}</li> + <li>{{jsxref("Math.exp()")}}</li> + <li>{{jsxref("Math.log()")}}</li> + <li>{{jsxref("Math.sqrt()")}}</li> + <li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators#Exponentiation" title="Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value. The standard arithmetic operators are addition (+), subtraction (-), multiplication (*), and division (/).">Exponentiation operator</a> {{experimental_inline}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/random/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/random/index.html new file mode 100644 index 0000000000..46aad728b8 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/random/index.html @@ -0,0 +1,94 @@ +--- +title: Math.random() +slug: Web/JavaScript/Reference/Global_Objects/Math/random +tags: + - JavaScript + - Math + - Math.random() + - Method + - 随机数 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/random +--- +<div>{{JSRef}}</div> + +<div><code><strong>Math.random()</strong></code> 函数返回一个浮点, 伪随机数在范围从<strong>0到</strong>小于<strong>1</strong>，也就是说，从0（包括0）往上，但是不包括1（排除1），然后您可以缩放到所需的范围。实现将初始种子选择到随机数生成算法;它不能被用户选择或重置。</div> + +<p>{{EmbedInteractiveExample("pages/js/math-random.html")}}</p> + +<div class="note"> +<p><code>Math.random()</code> <em>不能</em>提供像密码一样安全的随机数字。不要使用它们来处理有关安全的事情。使用Web Crypto API 来代替, 和更精确的{{domxref("RandomSource.getRandomValues()", "window.crypto.getRandomValues()")}} 方法.</p> +</div> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox notranslate"><code>Math.random()</code></pre> + +<h3 id="Parameters" name="Parameters">返回值</h3> + +<p>一个浮点型伪随机数字，在<code>0</code>（包括0）和<code>1</code>（不包括）之间。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<p>请注意, 由于 JavaScript 中的数字是 IEEE 754 浮点数字，具有最近舍入（ round-to-nearest-even）的行为, 因此以下函数的范围 (不包括<code>Math.random()</code> 本身) 并不准确。如果选择了非常大的边界 (2<sup>53</sup> 或更高), 在极罕见的情况下会计算通常-排除（usually-excluded）的上界。（注：round-to-nearest-even采用最近舍入的去偶数舍入的方式，对.5的舍入上，采用取偶数的方式）</p> + +<h3 id="得到一个大于等于0，小于1之间的随机数">得到一个大于等于0，小于1之间的随机数</h3> + +<pre class="brush: js notranslate">function getRandom() { + return Math.random(); +}</pre> + +<h3 id="得到一个两数之间的随机数">得到一个两数之间的随机数</h3> + +<p>这个例子返回了一个在指定值之间的随机数。这个值不小于 <code>min</code>（有可能等于），并且小于（不等于）<code>max</code>。</p> + +<pre class="brush: js notranslate">function getRandomArbitrary(min, max) { + return Math.random() * (max - min) + min; +} +</pre> + +<h3 id="得到一个两数之间的随机整数">得到一个两数之间的随机整数</h3> + +<p>这个例子返回了一个在指定值之间的随机整数。这个值不小于 <code>min</code> （如果 <code>min</code> 不是整数，则不小于 <code>min</code> 的向上取整数），且小于（不等于）<code>max</code>。</p> + +<pre class="brush: js line-numbers language-js notranslate"><code class="language-js"><span class="keyword token">function</span> <span class="function token">getRandomInt</span><span class="punctuation token">(</span>min<span class="punctuation token">,</span> max<span class="punctuation token">)</span> <span class="punctuation token">{</span> + min <span class="operator token">=</span> Math<span class="punctuation token">.</span><span class="function token">ceil</span><span class="punctuation token">(</span>min<span class="punctuation token">)</span><span class="punctuation token">;</span> + max <span class="operator token">=</span> Math<span class="punctuation token">.</span><span class="function token">floor</span><span class="punctuation token">(</span>max<span class="punctuation token">)</span><span class="punctuation token">;</span> + <span class="keyword token">return</span> Math<span class="punctuation token">.</span><span class="function token">floor</span><span class="punctuation token">(</span>Math<span class="punctuation token">.</span><span class="function token">random</span><span class="punctuation token">(</span><span class="punctuation token">)</span> <span class="operator token">*</span> <span class="punctuation token">(</span>max <span class="operator token">-</span> min<span class="punctuation token">)</span><span class="punctuation token">)</span> <span class="operator token">+</span> min<span class="punctuation token">;</span> </code>//不含最大值，含最小值<code class="language-js"> +<span class="punctuation token">}</span></code></pre> + +<div class="note"> +<p>也许很容易想到用 <code>Math.round()</code> 来实现，但是这会导致你的随机数处于一个不均匀的分布，这可能不符合你的需求。</p> +</div> + +<h3 id="得到一个两数之间的随机整数，包括两个数在内">得到一个两数之间的随机整数，包括两个数在内</h3> + +<p>上一个例子提到的函数 <code>getRandomInt()</code> 结果范围包含了最小值，但不含最大值。如果你的随机结果需要同时包含最小值和最大值，怎么办呢? <code>getRandomIntInclusive()</code> 函数可以实现。</p> + +<pre class="brush: js line-numbers language-js notranslate"><code class="language-js"><span class="keyword token">function</span> <span class="function token">getRandomIntInclusive</span><span class="punctuation token">(</span>min<span class="punctuation token">,</span> max<span class="punctuation token">)</span> <span class="punctuation token">{</span> + min <span class="operator token">=</span> Math<span class="punctuation token">.</span><span class="function token">ceil</span><span class="punctuation token">(</span>min<span class="punctuation token">)</span><span class="punctuation token">;</span> + max <span class="operator token">=</span> Math<span class="punctuation token">.</span><span class="function token">floor</span><span class="punctuation token">(</span>max<span class="punctuation token">)</span><span class="punctuation token">;</span> + <span class="keyword token">return</span> Math<span class="punctuation token">.</span><span class="function token">floor</span><span class="punctuation token">(</span>Math<span class="punctuation token">.</span><span class="function token">random</span><span class="punctuation token">(</span><span class="punctuation token">)</span> <span class="operator token">*</span> <span class="punctuation token">(</span>max <span class="operator token">-</span> min <span class="operator token">+</span> <span class="number token">1</span><span class="punctuation token">)</span><span class="punctuation token">)</span> <span class="operator token">+</span> min<span class="punctuation token">;</span> <span class="comment token">//含最大值，含最小值 </span> +<span class="punctuation token">}</span></code></pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范</th> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.random', 'Math.random')}}</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{Compat("javascript.builtins.Math.random")}}</p> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li><a href="https://wiki.developer.mozilla.org/en-US/docs/Web/API/RandomSource/getRandomValues" title="The documentation about this has not yet been written; please consider contributing!"><code>window.crypto.getRandomValues()</code></a></li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/round/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/round/index.html new file mode 100644 index 0000000000..c1fae674cc --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/round/index.html @@ -0,0 +1,356 @@ +--- +title: Math.round() +slug: Web/JavaScript/Reference/Global_Objects/Math/round +tags: + - Math.round() + - 四舍五入 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/round +--- +<p>{{JSRef}}</p> + +<p><code><strong>Math.round()</strong></code> 函数返回一个数字四舍五入后最接近的整数。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.round(<em>x</em>) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值。</dd> + <dt> + <h3 id="返回值">返回值</h3> + + <p>给定数字的值四舍五入到最接近的整数。</p> + </dt> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>如果参数的小数部分大于 0.5，则舍入到相邻的绝对值更大的整数。 如果参数的小数部分小于 0.5，则舍入到相邻的绝对值更小的整数。如果参数的小数部分恰好等于0.5，则舍入到相邻的在正无穷（+∞）方向上的整数。<strong>注意，与很多其他语言中的<code>round()函数</code>不同，<code>Math.round()并不总是舍入到远离0的方向（尤其是在负数的小数部分恰好等于0.5的情况下）。</code></strong></p> + +<p>因为 <code>round()</code> 是 <code>Math</code> 的静态方法，你应该直接使用 <code>Math.round()</code>，而不是作为你创建的 <code>Math</code> 对象的一个实例方法来使用（<code>Math</code>没有构造函数）。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<pre class="brush:js">x = Math.round(20.49); //20 +x = Math.round(20.5); //21 +x = Math.round(-20.5); //-20 +x = Math.round(-20.51); //-21 +</pre> + +<h3 id="Example:_Decimal_rounding" name="Example:_Decimal_rounding" style="line-height: 24px;">小数舍入</h3> + +<pre class="brush: js">// 闭包 +(function(){ + + /** + * Decimal adjustment of a number. + * + * @param {String} type The type of adjustment. + * @param {Number} value The number. + * @param {Integer} exp The exponent (the 10 logarithm of the adjustment base). + * @returns {Number} The adjusted value. + */ + function decimalAdjust(type, value, exp) { + // If the exp is undefined or zero... + if (typeof exp === 'undefined' || +exp === 0) { + return Math[type](value); + } + value = +value; + exp = +exp; + // If the value is not a number or the exp is not an integer... + if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) { + return NaN; + } + // Shift + value = value.toString().split('e'); + value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp))); + // Shift back + value = value.toString().split('e'); + return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp)); + } + + // Decimal round + if (!Math.round10) { + Math.round10 = function(value, exp) { + return decimalAdjust('round', value, exp); + }; + } + // Decimal floor + if (!Math.floor10) { + Math.floor10 = function(value, exp) { + return decimalAdjust('floor', value, exp); + }; + } + // Decimal ceil + if (!Math.ceil10) { + Math.ceil10 = function(value, exp) { + return decimalAdjust('ceil', value, exp); + }; + } + +})(); + +// Round +Math.round10(55.55, -1); // 55.6 +Math.round10(55.549, -1); // 55.5 +Math.round10(55, 1); // 60 +Math.round10(54.9, 1); // 50 +Math.round10(-55.55, -1); // -55.5 +Math.round10(-55.551, -1); // -55.6 +Math.round10(-55, 1); // -50 +Math.round10(-55.1, 1); // -60 +Math.round10(1.005, -2); // 1.01 -- compare this with Math.round(1.005*100)/100 above +// Floor +Math.floor10(55.59, -1); // 55.5 +Math.floor10(59, 1); // 50 +Math.floor10(-55.51, -1); // -55.6 +Math.floor10(-51, 1); // -60 +// Ceil +Math.ceil10(55.51, -1); // 55.6 +Math.ceil10(51, 1); // 60 +Math.ceil10(-55.59, -1); // -55.5 +Math.ceil10(-59, 1); // -50 +</pre> + +<p>或：</p> + +<pre class="brush: js">function round(number, precision) { + return Math.round(+number + 'e' + precision) / Math.pow(10, precision); + //same as: + //return Number(Math.round(+number + 'e' + precision) + 'e-' + precision); +} + +round(1.005, 2); //1.01 +</pre> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 0px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 19px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 38px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 57px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; 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position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1064px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1083px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1102px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1121px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1140px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1159px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1178px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1197px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1216px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1235px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1254px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1273px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1292px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1311px; background: 0px 0px;"> </div> + +<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 1330px; background: 0px 0px;"> </div> + +<h2 id="规范" style="margin-bottom: 20px; line-height: 30px;">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0.</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.15', 'Math.round')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.round', 'Math.round')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性" style="margin-bottom: 20px; line-height: 30px;">浏览器兼容性</h2> + +<div>{{CompatibilityTable}}</div> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th style="line-height: 16px;">Feature</th> + <th style="line-height: 16px;">Chrome</th> + <th style="line-height: 16px;">Firefox (Gecko)</th> + <th style="line-height: 16px;">Internet Explorer</th> + <th style="line-height: 16px;">Opera</th> + <th style="line-height: 16px;">Safari (WebKit)</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th style="line-height: 16px;">Feature</th> + <th style="line-height: 16px;">Android</th> + <th style="line-height: 16px;">Firefox Mobile (Gecko)</th> + <th style="line-height: 16px;">IE Phone</th> + <th style="line-height: 16px;">Opera Mobile</th> + <th style="line-height: 16px;">Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{CompatVersionUnknown}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also" style="margin-bottom: 20px; line-height: 30px;">相关链接</h2> + +<p></p> + +<ul> + <li>{{jsxref("Math.abs()")}}</li> + <li>{{jsxref("Math.ceil()")}}</li> + <li>{{jsxref("Math.floor()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/sign/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/sign/index.html new file mode 100644 index 0000000000..ca7678c9f0 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/sign/index.html @@ -0,0 +1,152 @@ +--- +title: Math.sign() +slug: Web/JavaScript/Reference/Global_Objects/Math/sign +tags: + - JavaScript + - Math + - Math.sign() +translation_of: Web/JavaScript/Reference/Global_Objects/Math/sign +--- +<div>{{JSRef}}</div> + +<div> </div> + +<p><strong><code>Math.sign()</code></strong> 函数返回一个数字的符号, 指示数字是正数，负数还是零。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.sign(<em>x</em>);</code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字.</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>因为 <code>sign </code>是 <code>Math </code>的一个静态方法，所以你应该使用 Math.sign() ，而不是作为你创建的一个Math对象的一种方法 （Math不是一个构造函数）。</p> + +<p>而不是作为您创建的Math对象的一种方法（Math不是构造函数）。</p> + +<p>此函数共有5种返回值, 分别是<strong> 1, -1, 0, -0, NaN.</strong> 代表的各是<strong>正数, 负数, 正零, 负零, NaN</strong>。</p> + +<p>传入该函数的参数会被<strong>隐式转换</strong>成数字类型。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="使用Math.sign()">使用Math.sign()</h3> + +<pre class="brush:js">Math.sign(3); // 1 +Math.sign(-3); // -1 +Math.sign("-3"); // -1 +Math.sign(0); // 0 +Math.sign(-0); // -0 +Math.sign(NaN); // NaN +Math.sign("foo"); // NaN +Math.sign(); // NaN +</pre> + +<h2 id="Compatibility" name="Compatibility">Polyfill</h2> + +<pre class="brush: js language-js"><code class="language-js"><span class="keyword token">function</span> <span class="function token">sign<span class="punctuation token">(</span></span>x<span class="punctuation token">)</span> <span class="punctuation token">{</span> + x <span class="operator token">=</span> <span class="operator token">+</span>x<span class="comment token"> ;// convert to a number +</span> <span class="keyword token">if</span> <span class="punctuation token">(</span>x <span class="operator token">===</span> <span class="number token">0</span> <span class="operator token">||</span> <span class="function token">isNaN<span class="punctuation token">(</span></span>x<span class="punctuation token">)</span><span class="punctuation token">)</span> + <span class="keyword token">return</span> x; + <span class="keyword token">return</span> x <span class="operator token">></span> <span class="number token">0</span> <span class="operator token">?</span> <span class="number token">1</span> <span class="punctuation token">:</span> <span class="operator token">-</span><span class="number token">1;</span> +<span class="punctuation token">}</span></code></pre> + +<p> </p> + +<pre><code>if (!Math.sign) { + Math.sign = function(x) { + // If x is NaN, the result is NaN. + // If x is -0, the result is -0. + // If x is +0, the result is +0. + // If x is negative and not -0, the result is -1. + // If x is positive and not +0, the result is +1. + x = +x; // convert to a number + if (x === 0 || isNaN(x)) { + return Number(x); + } + return x > 0 ? 1 : -1; + }; +}</code></pre> + +<p> </p> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.sign', 'Math.sign')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>38</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>25</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Global_Objects/Math", "Math")}} 对象</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/sin/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/sin/index.html new file mode 100644 index 0000000000..989c5af7e5 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/sin/index.html @@ -0,0 +1,80 @@ +--- +title: Math.sin() +slug: Web/JavaScript/Reference/Global_Objects/Math/sin +translation_of: Web/JavaScript/Reference/Global_Objects/Math/sin +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p><code><strong>Math.sin()</strong></code> 函数返回一个数值的正弦值。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox notranslate">Math.sin(<em>x</em>)</pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值（以弧度为单位）。</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p><code>sin</code> 方法返回一个 -1 到 1 之间的数值，表示给定角度（单位：弧度）的正弦值。</p> + +<p>由于 <code>sin</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.sin()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example_Using_Math.sin" name="Example:_Using_Math.sin">例子：使用 <code>Math.sin</code></h3> + +<pre class="brush:js notranslate">Math.sin(0); // 0 +Math.sin(1); // 0.8414709848078965 + +Math.sin(Math.PI / 2); // 1</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.16', 'Math.sin')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.sin', 'Math.sin')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ Compat("javascript.builtins.Math.sin") }}</p> + +<div id="compat-desktop"></div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math.acos()")}}</li> + <li>{{jsxref("Math.asin()")}}</li> + <li>{{jsxref("Math.atan()")}}</li> + <li>{{jsxref("Math.atan2()")}}</li> + <li>{{jsxref("Math.cos()")}}</li> + <li>{{jsxref("Math.tan()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/sinh/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/sinh/index.html new file mode 100644 index 0000000000..c9f0d376f9 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/sinh/index.html @@ -0,0 +1,123 @@ +--- +title: Math.sinh() +slug: Web/JavaScript/Reference/Global_Objects/Math/sinh +translation_of: Web/JavaScript/Reference/Global_Objects/Math/sinh +--- +<div>{{JSRef("Global_Objects", "Math")}}</div> + +<h2 id="Summary" name="Summary">概述</h2> + +<p> <code><strong>Math.sinh()</strong></code> 函数返回一个数字(单位为角度)的双曲正弦值.</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox notranslate">Math.sinh(<em>x</em>)</pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>任意数字 (单位为度).</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>双曲正弦的图像如下:</p> + +<p><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/1/17/Sinh.png" style="height: 300px; width: 300px;"></p> + +<h2 id="Examples" name="Examples">示例</h2> + +<pre class="brush:js notranslate">Math.sinh(0) // 0 +Math.sinh(1) // 1.1752011936438014 +Math.sinh("-1") // -1.1752011936438014 +Math.sinh("foo") // NaN +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.sinh', 'Math.sinh')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial defintion</td> + </tr> + </tbody> +</table> + +<h2 id="Polyfill">Polyfill</h2> + +<p>该函数可以使用 {{jsxref("Math.exp()")}}<code> 函数来实现</code>:</p> + +<pre class="brush: js language-js notranslate">function sinh(x){ + return (Math.exp(x) - Math.exp(-x)) / 2; +}</pre> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoDesktop("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatGeckoMobile("25")}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="See_also" name="See_also">相关链接</h2> + +<ul> + <li>{{jsxref("Math.acos()")}}</li> + <li>{{jsxref("Math.asin()")}}</li> + <li>{{jsxref("Math.atan()")}}</li> + <li>{{jsxref("Math.atan2()")}}</li> + <li>{{jsxref("Math.cos()")}}</li> + <li>{{jsxref("Math.tan()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/sqrt/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/sqrt/index.html new file mode 100644 index 0000000000..badb08802a --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/sqrt/index.html @@ -0,0 +1,81 @@ +--- +title: Math.sqrt() +slug: Web/JavaScript/Reference/Global_Objects/Math/sqrt +translation_of: Web/JavaScript/Reference/Global_Objects/Math/sqrt +--- +<div>{{JSRef}}</div> + +<p><code><strong>Math.sqrt()</strong></code> 函数返回一个数的平方根，即：</p> + +<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>≥</mo><mn>0</mn><mo>,</mo><mstyle mathvariant="monospace"><mrow><mi>M</mi><mi>a</mi><mi>t</mi><mi>h</mi><mo>.</mo><mi>s</mi><mi>q</mi><mi>r</mi><mi>t</mi><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><msqrt><mi>x</mi></msqrt><mo>=</mo><mtext>the unique</mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>≥</mo><mn>0</mn><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><msup><mi>y</mi><mn>2</mn></msup><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \geq 0, \mathtt{Math.sqrt(x)} = \sqrt{x} = \text{the unique} \; y \geq 0 \; \text{such that} \; y^2 = x</annotation></semantics></math></p> + +<p>{{EmbedInteractiveExample("pages/js/math-sqrt.html")}}</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox"><code>Math.sqrt(<em>x</em>) </code></pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数值</dd> +</dl> + +<h2 id="Description" name="Description">描述</h2> + +<p>如果参数 <code>number</code> 为负值，则 <code>sqrt</code> 返回{{jsxref("NaN")}}。</p> + +<p>由于 <code>sqrt</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.sqrt()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<h3 id="Example_Using_Math.sqrt" name="Example:_Using_Math.sqrt">使用 <code>Math.sqrt</code></h3> + +<pre><code>Math.sqrt(9); // 3 +Math.sqrt(2); // 1.414213562373095 + +Math.sqrt(1); // 1 +Math.sqrt(0); // 0 +Math.sqrt(-1); // NaN +Math.sqrt(-0); // -0</code></pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.17', 'Math.sqrt')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.sqrt', 'Math.sqrt')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{Compat("javascript.builtins.Math.sqrt")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>{{jsxref("Math.cbrt()")}}</li> + <li>{{jsxref("Math.exp()")}}</li> + <li>{{jsxref("Math.log()")}}</li> + <li>{{jsxref("Math.pow()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/sqrt1_2/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/sqrt1_2/index.html new file mode 100644 index 0000000000..47e0557901 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/sqrt1_2/index.html @@ -0,0 +1,100 @@ +--- +title: Math.SQRT1_2 +slug: Web/JavaScript/Reference/Global_Objects/Math/SQRT1_2 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/SQRT1_2 +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.SQRT1_2</strong></code> 属性表示 1/2 的平方根，约为 0.707：</p> +<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mi>Math.SQRT1_2</mi></mstyle><mo>=</mo><msqrt><mfrac><mn>1</mn><mn>2</mn></mfrac></msqrt><mo>=</mo><mfrac><mn>1</mn><msqrt><mn>2</mn></msqrt></mfrac><mo>≈</mo><mn>0.707</mn></mrow><annotation encoding="TeX">\mathtt{\mi{Math.SQRT1_2}} = \sqrt{\frac{1}{2}} = \frac{1}{\sqrt{2}} \approx 0.707</annotation></semantics></math></p> +<div> + {{js_property_attributes(0,0,0)}}</div> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>SQRT1_2</code> 是 <code>Math</code> 对象的静态属性，所以应该像这样使用：<code>Math.SQRT1_2</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_SQRT1_2" name="Example:_Using_SQRT1_2">例子：使用 <code>SQRT1_2</code></h3> +<p>下面的函数返回 1/2 的平方根：</p> +<pre class="brush:js">function getRoot1_2() { + return Math.SQRT1_2 +} + +getRoot1_2() // 0.7071067811865476</pre> +<p></p> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.7', 'Math.SQRT1_2')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.sqrt1_2', 'Math.SQRT1_2')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/sqrt2/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/sqrt2/index.html new file mode 100644 index 0000000000..a9eb2ddcd4 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/sqrt2/index.html @@ -0,0 +1,96 @@ +--- +title: Math.SQRT2 +slug: Web/JavaScript/Reference/Global_Objects/Math/SQRT2 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/SQRT2 +--- +<p>{{JSRef("Global_Objects", "Math")}}</p> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.SQRT2</strong></code> 属性表示 2 的平方根，约为 1.414：</p> +<h2 id="Description" name="Description">描述</h2> +<p>由于 <code>SQRT2</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.SQRT2</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是构造函数）。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.SQRT2" name="Example:_Using_Math.SQRT2">例子：使用 <code>Math.SQRT2</code></h3> +<p>下面的函数返回 2 的平方根：</p> +<pre class="brush:js">function getRoot2() { + return Math.SQRT2; +} + +getRoot2(); // 1.4142135623730951</pre> +<h2 id="规范" style="margin-bottom: 20px; line-height: 30px;">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.1.8', 'Math.SQRT2')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.sqrt2', 'Math.SQRT2')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性" style="margin-bottom: 20px; line-height: 30px;">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th style="line-height: 16px;">Feature</th> + <th style="line-height: 16px;">Chrome</th> + <th style="line-height: 16px;">Firefox (Gecko)</th> + <th style="line-height: 16px;">Internet Explorer</th> + <th style="line-height: 16px;">Opera</th> + <th style="line-height: 16px;">Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th style="line-height: 16px;">Feature</th> + <th style="line-height: 16px;">Android</th> + <th style="line-height: 16px;">Chrome for Android</th> + <th style="line-height: 16px;">Firefox Mobile (Gecko)</th> + <th style="line-height: 16px;">IE Mobile</th> + <th style="line-height: 16px;">Opera Mobile</th> + <th style="line-height: 16px;">Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<h2 id="See_also" name="See_also" style="margin-bottom: 20px; line-height: 30px;">相关链接</h2> +<ul> + <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li> +</ul> +<p></p> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/tan/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/tan/index.html new file mode 100644 index 0000000000..9e2464d76e --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/tan/index.html @@ -0,0 +1,107 @@ +--- +title: Math.tan() +slug: Web/JavaScript/Reference/Global_Objects/Math/tan +translation_of: Web/JavaScript/Reference/Global_Objects/Math/tan +--- +<div> + {{JSRef("Global_Objects", "Math")}}</div> +<h2 id="Summary" name="Summary">概述</h2> +<p><code><strong>Math.tan()</strong></code> 方法返回一个数值的正切值。</p> +<h2 id="Syntax" name="Syntax">语法</h2> +<pre class="syntaxbox">Math.tan(<em>x</em>)</pre> +<h3 id="Parameters" name="Parameters">参数</h3> +<dl> + <dt> + <code>x</code></dt> + <dd> + 一个数值，表示一个角（单位：弧度）。</dd> +</dl> +<h2 id="Description" name="Description">描述</h2> +<p><code>tan</code> 方法返回一个数值，表示一个角的正切值。</p> +<p>由于 <code>tan</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用 <code>Math.tan()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p> +<h2 id="Examples" name="Examples">示例</h2> +<h3 id="Example:_Using_Math.tan" name="Example:_Using_Math.tan">例子：使用 <code>Math.tan</code></h3> +<p>下面的函数返回变量 <code>x</code> 的正切值：</p> +<pre class="brush:js">function getTan(x) { + return Math.tan(x); +}</pre> +<p>由于 <code>Math.tan()</code> 函数接受弧度数值，但是通常使用度更方便，下面的函数可以接受以度为单位的数值，将其转为弧度，然后返回其正切值。</p> +<pre class="brush:js">function getTanDeg(deg) { + var rad = deg * Math.PI/180; + return Math.tan(rad); +} +</pre> +<h2 id="规范">规范</h2> +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范版本</th> + <th scope="col">规范状态</th> + <th scope="col">注解</th> + </tr> + <tr> + <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td> + <td>Standard</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.18', 'Math.tan')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-math.tan', 'Math.tan')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + </tbody> +</table> +<h2 id="浏览器兼容性">浏览器兼容性</h2> +<p>{{ CompatibilityTable() }}</p> +<div id="compat-desktop"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<div id="compat-mobile"> + <table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> + </table> +</div> +<p> </p> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/tanh/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/tanh/index.html new file mode 100644 index 0000000000..9a3eb0f21d --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/tanh/index.html @@ -0,0 +1,85 @@ +--- +title: Math.tanh() +slug: Web/JavaScript/Reference/Global_Objects/Math/tanh +tags: + - ECMAScript6 + - JavaScript + - Math + - Method + - tanh + - 双曲正切 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/tanh +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.tanh()</code></strong> 函数将会返回一个数的双曲正切函数值，公式如下：</p> + +<p><math display="block"><semantics><mrow><mo lspace="0em" rspace="0em">tanh</mo><mi>x</mi><mo>=</mo><mfrac><mrow><mo lspace="0em" rspace="0em">sinh</mo><mi>x</mi></mrow><mrow><mo lspace="0em" rspace="0em">cosh</mo><mi>x</mi></mrow></mfrac><mo>=</mo><mfrac><mrow><msup><mi>e</mi><mi>x</mi></msup><mo>-</mo><msup><mi>e</mi><mrow><mo>-</mo><mi>x</mi></mrow></msup></mrow><mrow><msup><mi>e</mi><mi>x</mi></msup><mo>+</mo><msup><mi>e</mi><mrow><mo>-</mo><mi>x</mi></mrow></msup></mrow></mfrac><mo>=</mo><mfrac><mrow><msup><mi>e</mi><mrow><mn>2</mn><mi>x</mi></mrow></msup><mo>-</mo><mn>1</mn></mrow><mrow><msup><mi>e</mi><mrow><mn>2</mn><mi>x</mi></mrow></msup><mo>+</mo><mn>1</mn></mrow></mfrac></mrow><annotation encoding="TeX">\tanh x = \frac{\sinh x}{\cosh x} = \frac {e^x - e^{-x}} {e^x + e^{-x}} = \frac{e^{2x} - 1}{e^{2x}+1}</annotation></semantics></math></p> + +<div>{{EmbedInteractiveExample("pages/js/math-tanh.html")}}</div> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>Math.tanh(<var>x</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>待计算的数字。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>所给数字的双曲正切值。</p> + +<h2 id="描述">描述</h2> + +<p>因为 <code>tanh()</code> 是 <code>Math</code> 的静态方法，所以总应该直接调用 <code>Math.tanh()</code> ，而不是创建 <code>Math</code> 对象再调用该方法（<code>Math</code> 不是一个构造函数）。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Math.tanh">使用 <code>Math.tanh()</code></h3> + +<pre class="brush: js">Math.tanh(0); // 0 +Math.tanh(Infinity); // 1 +Math.tanh(1); // 0.7615941559557649 +</pre> + +<h2 id="向下兼容">向下兼容</h2> + +<p><code>tanh()</code> 可以通过 {{jsxref("Math.exp()")}} 函数实现：</p> + +<pre class="brush: js">Math.tanh = Math.tanh || function(x){ + var a = Math.exp(+x), b = Math.exp(-x); + return a == Infinity ? 1 : b == Infinity ? -1 : (a - b) / (a + b); +}</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范</th> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.tanh', 'Math.tanh')}}</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> + +<p>{{Compat("javascript.builtins.Math.tanh")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>{{jsxref("Math.acosh()")}}</li> + <li>{{jsxref("Math.asinh()")}}</li> + <li>{{jsxref("Math.atanh()")}}</li> + <li>{{jsxref("Math.cosh()")}}</li> + <li>{{jsxref("Math.sinh()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/trunc/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/trunc/index.html new file mode 100644 index 0000000000..f260b85c58 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/trunc/index.html @@ -0,0 +1,116 @@ +--- +title: Math.trunc() +slug: Web/JavaScript/Reference/Global_Objects/Math/trunc +tags: + - ECMAScript 2015 + - JavaScript + - Math + - Method +translation_of: Web/JavaScript/Reference/Global_Objects/Math/trunc +--- +<div>{{JSRef}}</div> + +<p><code><strong>Math.trunc()</strong></code> 方法会将数字的小数部分去掉，只保留整数部分。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox">Math.trunc(<em>value</em>)</pre> + +<h3 id="Parameters" name="Parameters">参数</h3> + +<dl> + <dt><code>value</code></dt> + <dd>任意数字</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>给定数字的整数部分</p> + +<h2 id="Description" name="Description">描述</h2> + +<p>不像 <code>Math</code> 的其他三个方法： {{jsxref("Math.floor()")}}、{{jsxref("Math.ceil()")}}、{{jsxref("Math.round()")}} ，<code>Math.trunc()</code> 的执行逻辑很简单，仅仅是<strong>删除</strong>掉数字的小数部分和小数点，不管参数是正数还是负数。</p> + +<p>传入该方法的参数会被隐式转换成数字类型。</p> + +<p>因为 <code>trunc()</code> 是 <code>Math</code> 对象的静态方法，你必须用 <code>Math.trunc()</code> 来使用，而不是调用你创建的 <code>Math</code> 对象的一个实例方法（<code>Math</code> 没有构造函数）</p> + +<h2 id="Examples" name="Examples">示例</h2> + +<pre class="brush:js">Math.trunc(13.37) // 13 +Math.trunc(42.84) // 42 +Math.trunc(0.123) // 0 +Math.trunc(-0.123) // -0 +Math.trunc("-1.123") // -1 +Math.trunc(NaN) // NaN +Math.trunc("foo") // NaN +Math.trunc() // NaN</pre> + +<h2 id="Polyfill">Polyfill</h2> + +<pre><code>if (!Math.trunc) { + Math.trunc = function(v) { + v = +v; + if (!isFinite(v)) return v; + + return (v - v % 1) || (v < 0 ? -0 : v === 0 ? v : 0); + + // 返回: + // 0 -> 0 + // -0 -> -0 + // 0.2 -> 0 + // -0.2 -> -0 + // 0.7 -> 0 + // -0.7 -> -0 + // Infinity -> Infinity + // -Infinity -> -Infinity + // NaN -> NaN + // null -> 0 + }; +}</code> +</pre> + +<p>或:</p> + +<pre><code>if (!Math.trunc) { + Math.trunc = function(v) { + v = +v; + return (v - v % 1) || (!isFinite(v) || v === 0 ? v : v < 0 ? -0 : 0); + }; +}</code></pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范名称</th> + <th scope="col">规范状态</th> + <th scope="col">备注</th> + </tr> + <tr> + <td>{{SpecName('ES2015', '#sec-math.trunc', 'Math.trunc')}}</td> + <td>{{Spec2('ES2015')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.trunc', 'Math.trunc')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{Compat("javascript.builtins.Math.trunc")}}</p> + +<p><strong style="color: #4d4e53; font-size: 2.14286rem; font-weight: 700; letter-spacing: -1px;">相关链接</strong></p> + +<ul> + <li>{{jsxref("Math.abs()")}}</li> + <li>{{jsxref("Math.ceil()")}}</li> + <li>{{jsxref("Math.floor()")}}</li> + <li>{{jsxref("Math.round()")}}</li> + <li>{{jsxref("Math.sign()")}}</li> +</ul> diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/反双曲余弦值/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/反双曲余弦值/index.html new file mode 100644 index 0000000000..7869661836 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/反双曲余弦值/index.html @@ -0,0 +1,91 @@ +--- +title: Math.acosh() +slug: Web/JavaScript/Reference/Global_Objects/Math/反双曲余弦值 +tags: + - JavaScript + - 双曲函数 + - 数学 + - 方法 +translation_of: Web/JavaScript/Reference/Global_Objects/Math/acosh +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.acosh()</code> </strong>函数返回一个数的反双曲余弦值，即：</p> + +<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>≥</mo><mn>1</mn><mo>,</mo><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.acosh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="thinmathspace">arcosh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>≥</mo><mn>0</mn><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">cosh</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \geq 1, \mathtt{\operatorname{Math.acosh}(x)} = \operatorname{arcosh}(x) = \text{ 唯一的} \; y \geq 0 \; \text{使得} \; \cosh(y) = x</annotation></semantics></math></p> + +<div>{{EmbedInteractiveExample("pages/js/math-acosh.html")}}</div> + + + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>Math.acosh(<var>x</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一个数字。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>返回给定数的反双曲余弦值，如果该数小于 <strong>1</strong> 则返回 {{jsxref("NaN")}}。</p> + +<h2 id="描述">描述</h2> + +<p>因为 <code>acosh()</code> 是 <code>Math</code> 的静态方法，所以总应该直接调用 <code>Math.acosh()</code> ，而不是创建 <code>Math</code> 对象再调用该方法（<code>Math</code> 不是一个构造函数）。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Math.acosh">使用 <code>Math.acosh()</code></h3> + +<pre class="brush: js">Math.acosh(-1); // NaN +Math.acosh(0); // NaN +Math.acosh(0.5); // NaN +Math.acosh(1); // 0 +Math.acosh(2); // 1.3169578969248166 +</pre> + +<p>当参数小于1时， <code>Math.acosh()</code>将返回 {{jsxref("NaN")}}。</p> + +<h2 id="向下兼容">向下兼容</h2> + +<p>当 <math><semantics><mrow><mi>x</mi><mo>≥</mo><mn>1</mn></mrow><annotation encoding="TeX">x \geq 1</annotation></semantics></math> 时，都有 <math><semantics><mrow><mo lspace="0em" rspace="thinmathspace">arcosh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mo lspace="0em" rspace="0em">ln</mo><mrow><mo>(</mo><mrow><mi>x</mi><mo>+</mo><msqrt><mrow><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>1</mn></mrow></msqrt></mrow><mo>)</mo></mrow></mrow><annotation encoding="TeX">\operatorname {arcosh} (x) = \ln \left(x + \sqrt{x^{2} - 1} \right)</annotation></semantics></math> ，因此可以使用以下函数实现：</p> + +<pre class="brush: js">Math.acosh = Math.acosh || function(x) { + return Math.log(x + Math.sqrt(x * x - 1)); +}; +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <thead> + <tr> + <th scope="col">Specification</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.acosh', 'Math.acosh')}}</td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> + +<p>{{Compat("javascript.builtins.Math.acosh")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>{{jsxref("Math.asinh()")}}</li> + <li>{{jsxref("Math.atanh()")}}</li> + <li>{{jsxref("Math.cosh()")}}</li> + <li>{{jsxref("Math.sinh()")}}</li> + <li>{{jsxref("Math.tanh()")}}</li> +</ul> |