diff options
Diffstat (limited to 'files/zh-tw/web/javascript/reference/global_objects/math/abs/index.html')
| -rw-r--r-- | files/zh-tw/web/javascript/reference/global_objects/math/abs/index.html | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/files/zh-tw/web/javascript/reference/global_objects/math/abs/index.html b/files/zh-tw/web/javascript/reference/global_objects/math/abs/index.html new file mode 100644 index 0000000000..91be97bc11 --- /dev/null +++ b/files/zh-tw/web/javascript/reference/global_objects/math/abs/index.html @@ -0,0 +1,104 @@ +--- +title: Math.abs() +slug: Web/JavaScript/Reference/Global_Objects/Math/abs +tags: + - JavaScript + - Math + - Method + - Reference +translation_of: Web/JavaScript/Reference/Global_Objects/Math/abs +--- +<div>{{JSRef}}</div> + +<p><strong><code>Math.abs()</code></strong> 函式會回傳一個數字的絕對值,即為:</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><mi>0</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> + +<div>{{EmbedInteractiveExample("pages/js/math-abs.html")}}</div> + + + +<h2 id="語法">語法</h2> + +<pre class="syntaxbox">Math.abs(<var>x</var>)</pre> + +<h3 id="參數">參數</h3> + +<dl> + <dt><code>x</code></dt> + <dd>一個數字。</dd> +</dl> + +<h3 id="回傳值">回傳值</h3> + +<p>給定數字的絕對值。</p> + +<h2 id="描述">描述</h2> + +<p>Because <code>abs()</code> is a static method of <code>Math</code>, you always use it as <code>Math.abs()</code>, rather than as a method of a <code>Math</code> object you created (<code>Math</code> is not a constructor).</p> + +<h2 id="範例">範例</h2> + +<h3 id="Math.abs()_的行為"><code>Math.abs()</code> 的行為</h3> + +<p>Passing an empty object, an array with more than one member, a non-numeric string or {{jsxref("undefined")}}/empty variable returns {{jsxref("NaN")}}. Passing {{jsxref("null")}}, an empty string or an empty array returns 0.</p> + +<pre class="brush: js" dir="rtl">Math.abs('-1'); // 1 +Math.abs(-2); // 2 +Math.abs(null); // 0 +Math.abs(''); // 0 +Math.abs([]); // 0 +Math.abs([2]); // 2 +Math.abs([1,2]); // NaN +Math.abs({}); // NaN +Math.abs('string'); // NaN +Math.abs(); // NaN +</pre> + +<h2 id="規範">規範</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('ES1')}}</td> + <td>{{Spec2('ES1')}}</td> + <td>Initial definition. Implemented in JavaScript 1.0.</td> + </tr> + <tr> + <td>{{SpecName('ES5.1', '#sec-15.8.2.1', '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> + <tr> + <td>{{SpecName('ESDraft', '#sec-math.abs', 'Math.abs')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="瀏覽器相容性">瀏覽器相容性</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.abs")}}</p> + +<h2 id="參見">參見</h2> + +<ul> + <li>{{jsxref("Math.ceil()")}}</li> + <li>{{jsxref("Math.floor()")}}</li> + <li>{{jsxref("Math.round()")}}</li> + <li>{{jsxref("Math.sign()")}}</li> + <li>{{jsxref("Math.trunc()")}}</li> +</ul> |
