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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
commit | 33058f2b292b3a581333bdfb21b8f671898c5060 (patch) | |
tree | 51c3e392513ec574331b2d3f85c394445ea803c6 /files/zh-cn/web/javascript/reference/global_objects/uint8clampedarray | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/javascript/reference/global_objects/uint8clampedarray/index.html b/files/zh-cn/web/javascript/reference/global_objects/uint8clampedarray/index.html new file mode 100644 index 0000000000..86028a8fb9 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/uint8clampedarray/index.html @@ -0,0 +1,280 @@ +--- +title: Uint8ClampedArray +slug: Web/JavaScript/Reference/Global_Objects/Uint8ClampedArray +translation_of: Web/JavaScript/Reference/Global_Objects/Uint8ClampedArray +--- +<div>{{JSRef}}</div> + +<p><strong><code>Uint8ClampedArray</code>(8位无符号整型固定数组)</strong> 类型化数组表示一个由值固定在0-255区间的8位无符号整型组成的数组;如果你指定一个在 [0,255] 区间外的值,它将被替换为0或255;如果你指定一个非整数,那么它将被设置为最接近它的整数。(数组)内容被初始化为0。一旦(数组)被创建,你可以使用对象的方法引用数组里的元素,或使用标准的数组索引语法(即使用方括号标记)。</p> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox notranslate">new Uint8ClampedArray(length); +new Uint8ClampedArray(typedArray); +new Uint8ClampedArray(object); +new Uint8ClampedArray(buffer [, byteOffset [, length]]);</pre> + +<p>关于构造函数语法和参数的更多信息,参见 <em><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray#Syntax">TypedArray</a></em>。</p> + +<h2 id="属性">属性</h2> + +<dl> + <dt>{{jsxref("TypedArray.BYTES_PER_ELEMENT", "Uint8ClampedArray.BYTES_PER_ELEMENT")}}</dt> + <dd>返回元素大小的一个数值。对 <code>Uint8ClampedArray</code> 而言是1。</dd> + <dt>{{jsxref("TypedArray.prototype.length", "Uint8ClampedArray.prototype.length")}}</dt> + <dd>静态长度属性值为0。对于实际长度(元素的数量),见 {{jsxref("TypedArray.prototype.length", "Uint8ClampedArray.prototype.length")}}。</dd> + <dt>{{jsxref("TypedArray.name", "Uint8ClampedArray.name")}}</dt> + <dd>返回构造函数名的字符串值。对 <code>Uint8ClampedArray</code> 类型而言:"Uint8ClampedArray"。</dd> + <dt>{{jsxref("TypedArray.prototype", "Uint8ClampedArray.prototype")}}</dt> + <dd>原型是 <em>TypedArray</em> (类型化数组)对象。</dd> +</dl> + +<h2 id="方法">方法</h2> + +<dl> + <dt>{{jsxref("TypedArray.from", "Uint8ClampedArray.from()")}}</dt> + <dd>从一个类数组或可枚举对象创建一个新的 <code>Uint8ClampedArray</code>。参见 {{jsxref("Array.from()")}}。</dd> + <dt>{{jsxref("TypedArray.of", "Uint8ClampedArray.of()")}}</dt> + <dd>通过一个可选数量参数来创建一个新的 <code>Uint8ClampedArray</code>。参见 {{jsxref("Array.of()")}}。</dd> +</dl> + +<h2 id="Uint8ClampedArray_原型">Uint8ClampedArray 原型</h2> + +<p>所有的 <code>Uint8ClampedArray</code> 对象继承自 {{jsxref("TypedArray.prototype", "%TypedArray%.prototype")}}。</p> + +<h3 id="属性_2">属性</h3> + +<dl> + <dt><code>Uint8ClampedArray.prototype.constructor</code></dt> + <dd>返回创建一个实例原型的函数。这是 <code>Uint8ClampedArray</code> 默认的构造函数。</dd> + <dt>{{jsxref("TypedArray.prototype.buffer", "Uint8ClampedArray.prototype.buffer")}} {{readonlyInline}}</dt> + <dd>返回由 <code>Uint8ClampedArray</code> 引用的 {{jsxref("ArrayBuffer")}} 。在创建时所固定下来,因此<strong>只能读取</strong>。</dd> + <dt>{{jsxref("TypedArray.prototype.byteLength", "Uint8ClampedArray.prototype.byteLength")}} {{readonlyInline}}</dt> + <dd>返回从 {{jsxref("ArrayBuffer")}} 开始的 <code>Uint8ClampedArray</code> 的(字节的)长度。在创建时所固定下来,因此<strong>只能读取</strong>。</dd> + <dt>{{jsxref("TypedArray.prototype.byteOffset", "Uint8ClampedArray.prototype.byteOffset")}} {{readonlyInline}}</dt> + <dd>返回从 {{jsxref("ArrayBuffer")}} 开始的 <code>Uint8ClampedArray</code> 的(字节的)偏移。在创建时所固定下来,因此<strong>只能读取</strong>。</dd> + <dt>{{jsxref("TypedArray.prototype.length", "Uint8ClampedArray.prototype.length")}} {{readonlyInline}}</dt> + <dd>返回 <code>UintClamped8Array</code> 具有的元素数量。在创建时所固定下来,因此<strong>只能读取</strong>。</dd> +</dl> + +<h3 id="方法_2">方法</h3> + +<dl> + <dt>{{jsxref("TypedArray.copyWithin", "Uint8ClampedArray.prototype.copyWithin()")}}</dt> + <dd>复制数组内一段数组元素的序列。参见 {{jsxref("Array.prototype.copyWithin()")}}。</dd> + <dt>{{jsxref("TypedArray.entries", "Uint8ClampedArray.prototype.entries()")}}</dt> + <dd>返回一个新的包含数组中每个索引对应的键/值对的数组迭代器对象。参见 {{jsxref("Array.prototype.entries()")}}。</dd> + <dt>{{jsxref("TypedArray.every", "Uint8ClampedArray.prototype.every()")}}</dt> + <dd>测试数组里的所有元素是否通过所提供的函数的测试。参见 {{jsxref("Array.prototype.every()")}}。</dd> + <dt>{{jsxref("TypedArray.fill", "Uint8ClampedArray.prototype.fill()")}}</dt> + <dd>用一个固定值填充一个数组内的从起始索引到结束索引的全部元素。参见 {{jsxref("Array.prototype.fill()")}}。</dd> + <dt>{{jsxref("TypedArray.filter", "Uint8ClampedArray.prototype.filter()")}}</dt> + <dd>由该数组中所有经所提供的筛选函数返回为 true 的元素创建一个新数组。参见 {{jsxref("Array.prototype.filter()")}}。</dd> + <dt>{{jsxref("TypedArray.find", "Uint8ClampedArray.prototype.find()")}}</dt> + <dd>如果数组里的一个元素符合所提供的测试函数则返回找到的这个值,如果没有找到则返回 <code>undefined</code>。参见 {{jsxref("Array.prototype.find()")}}。</dd> + <dt>{{jsxref("TypedArray.findIndex", "Uint8ClampedArray.prototype.findIndex()")}}</dt> + <dd>如果数组里的一个元素符合所提供的测试函数则返回找到的索引,如果没有找到则返回 -1。参见 {{jsxref("Array.prototype.findIndex()")}}。</dd> + <dt>{{jsxref("TypedArray.forEach", "Uint8ClampedArray.prototype.forEach()")}}</dt> + <dd>对数组内的每个元素调用一个函数。参见 {{jsxref("Array.prototype.forEach()")}}。</dd> + <dt>{{jsxref("TypedArray.includes", "Uint8ClampedArray.prototype.includes()")}} {{experimental_inline}}</dt> + <dd>确定一个类型化数组是否包含一个特定的元素,对应地返回 <code>true</code> 或 <code>false</code>。参见 {{jsxref("Array.prototype.includes()")}}。</dd> + <dt>{{jsxref("TypedArray.indexOf", "Uint8ClampedArray.prototype.indexOf()")}}</dt> + <dd>Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found. See also {{jsxref("Array.prototype.indexOf()")}}.</dd> + <dt>{{jsxref("TypedArray.join", "Uint8ClampedArray.prototype.join()")}}</dt> + <dd>Joins all elements of an array into a string. See also {{jsxref("Array.prototype.join()")}}.</dd> + <dt>{{jsxref("TypedArray.keys", "Uint8ClampedArray.prototype.keys()")}}</dt> + <dd>Returns a new <code>Array Iterator</code> that contains the keys for each index in the array. See also {{jsxref("Array.prototype.keys()")}}.</dd> + <dt>{{jsxref("TypedArray.lastIndexOf", "Uint8ClampedArray.prototype.lastIndexOf()")}}</dt> + <dd>Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found. See also {{jsxref("Array.prototype.lastIndexOf()")}}.</dd> + <dt>{{jsxref("TypedArray.map", "Uint8ClampedArray.prototype.map()")}}</dt> + <dd>Creates a new array with the results of calling a provided function on every element in this array. See also {{jsxref("Array.prototype.map()")}}.</dd> + <dt>{{jsxref("TypedArray.move", "Uint8ClampedArray.prototype.move()")}} {{non-standard_inline}} {{unimplemented_inline}}</dt> + <dd>Former non-standard version of {{jsxref("TypedArray.copyWithin", "Uint8ClampedArray.prototype.copyWithin()")}}.</dd> + <dt>{{jsxref("TypedArray.reduce", "Uint8ClampedArray.prototype.reduce()")}}</dt> + <dd>Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value. See also {{jsxref("Array.prototype.reduce()")}}.</dd> + <dt>{{jsxref("TypedArray.reduceRight", "Uint8ClampedArray.prototype.reduceRight()")}}</dt> + <dd>Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value. See also {{jsxref("Array.prototype.reduceRight()")}}.</dd> + <dt>{{jsxref("TypedArray.reverse", "Uint8ClampedArray.prototype.reverse()")}}</dt> + <dd>Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first. See also {{jsxref("Array.prototype.reverse()")}}.</dd> + <dt>{{jsxref("TypedArray.set", "Uint8ClampedArray.prototype.set()")}}</dt> + <dd>Stores multiple values in the typed array, reading input values from a specified array.</dd> + <dt>{{jsxref("TypedArray.slice", "Uint8ClampedArray.prototype.slice()")}}</dt> + <dd>Extracts a section of an array and returns a new array. See also {{jsxref("Array.prototype.slice()")}}.</dd> + <dt>{{jsxref("TypedArray.some", "Uint8ClampedArray.prototype.some()")}}</dt> + <dd>Returns true if at least one element in this array satisfies the provided testing function. See also {{jsxref("Array.prototype.some()")}}.</dd> + <dt>{{jsxref("TypedArray.sort", "Uint8ClampedArray.prototype.sort()")}}</dt> + <dd>Sorts the elements of an array in place and returns the array. See also {{jsxref("Array.prototype.sort()")}}.</dd> + <dt>{{jsxref("TypedArray.subarray", "Uint8ClampedArray.prototype.subarray()")}}</dt> + <dd>Returns a new <code>Uint8ClampedArray</code> from the given start and end element index.</dd> + <dt>{{jsxref("TypedArray.values", "Uint8ClampedArray.prototype.values()")}}</dt> + <dd>Returns a new <code>Array Iterator</code> object that contains the values for each index in the array. See also {{jsxref("Array.prototype.values()")}}.</dd> + <dt>{{jsxref("TypedArray.toLocaleString", "Uint8ClampedArray.prototype.toLocaleString()")}}</dt> + <dd>Returns a localized string representing the array and its elements. See also {{jsxref("Array.prototype.toLocaleString()")}}.</dd> + <dt>{{jsxref("TypedArray.toString", "Uint8ClampedArray.prototype.toString()")}}</dt> + <dd>Returns a string representing the array and its elements. See also {{jsxref("Array.prototype.toString()")}}.</dd> + <dt>{{jsxref("TypedArray.@@iterator", "Uint8ClampedArray.prototype[@@iterator]()")}}</dt> + <dd>Returns a new <code>Array Iterator</code> object that contains the values for each index in the array.</dd> +</dl> + +<h2 id="实例">实例</h2> + +<p>创建一个 <code>Uint8ClampedArray</code> 的不同方式:</p> + +<pre class="brush: js notranslate">// From a length +var uintc8 = new Uint8ClampedArray(2); +uintc8[0] = 42; +uintc8[1] = 1337; +console.log(uintc8[0]); // 42 +console.log(uintc8[1]); // 255 (clamped) +console.log(uintc8.length); // 2 +console.log(uintc8.BYTES_PER_ELEMENT); // 1 + +// From an array +var arr = new Uint8ClampedArray([21,31]); +console.log(arr[1]); // 31 + +// From another TypedArray +var x = new Uint8ClampedArray([21, 31]); +var y = new Uint8ClampedArray(x); +console.log(y[0]); // 21 + +// From an ArrayBuffer +var buffer = new ArrayBuffer(8); +var z = new Uint8ClampedArray(buffer, 1, 4); + +// From an iterable +var iterable = function*(){ yield* [1,2,3]; }(); +var uintc8 = new Uint8ClampedArray(iterable); +// Uint8ClampedArray[1, 2, 3] +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范</th> + <th scope="col">状态</th> + <th scope="col">注释</th> + </tr> + <tr> + <td>{{SpecName('Typed Array')}}</td> + <td>{{Spec2('Typed Array')}}</td> + <td>已由 ECMAScript 2015 替代。</td> + </tr> + <tr> + <td>{{SpecName('ES6', '#table-49', 'TypedArray constructors')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>最初定义在一份 ECMA 标准中。规定 <code>new</code> 是必需的。</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#table-49', 'TypedArray constructors')}}</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>特性</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>基础支持</td> + <td>7.0</td> + <td>{{ CompatGeckoDesktop(2) }}</td> + <td>11 (as of <a href="https://support.microsoft.com/en-us/kb/2929437">KB2929437</a>)</td> + <td>11.6</td> + <td>5.1</td> + </tr> + <tr> + <td>需要使用 <code>new</code></td> + <td>{{CompatUnknown}}</td> + <td>{{ CompatGeckoDesktop(44) }}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + </tr> + <tr> + <td>构造函数中可枚举</td> + <td>{{CompatUnknown}}</td> + <td>{{ CompatGeckoDesktop(52) }}</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>特性</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>基础支持</td> + <td>4.0</td> + <td>{{CompatVersionUnknown}}</td> + <td>{{ CompatGeckoMobile(2) }}</td> + <td>{{CompatVersionUnknown}}</td> + <td>11.6</td> + <td>4.2</td> + </tr> + <tr> + <td>需要使用 <code>new</code></td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{ CompatGeckoMobile(44) }}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + </tr> + <tr> + <td>构造函数中可枚举</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{ CompatGeckoMobile(52) }}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="兼容性注意事项">兼容性注意事项</h2> + +<p>从 ECMAScript 2015 开始, <code>Uint8ClampedArray</code> 构造函数需要用一个 {{jsxref("Operators/new", "new")}} 操作符来构建。从现在开始,不使用 <code>new</code> 来调用一个 <code>Uint8ClampedArray</code> 构造函数将会抛出一个 {{jsxref("TypeError")}}。</p> + +<pre class="brush: js example-bad notranslate">var dv = Uint8ClampedArray([1, 2, 3]); +// TypeError: calling a builtin Uint8ClampedArray constructor +// without new is forbidden</pre> + +<pre class="brush: js example-good notranslate">var dv = new Uint8ClampedArray([1, 2, 3]);</pre> + +<h2 id="参见">参见</h2> + +<ul> + <li><a href="/en-US/docs/Web/JavaScript/Typed_arrays">JavaScript typed arrays</a></li> + <li>{{jsxref("ArrayBuffer")}}</li> + <li>{{jsxref("DataView")}}</li> +</ul> |