path: root/files/zh-cn/web/javascript/reference/global_objects/int8array/index.html

---
title: Int8Array
slug: Web/JavaScript/Reference/Global_Objects/Int8Array
tags:
  - Int8Array
  - 构造器
  - 特定类型数组
translation_of: Web/JavaScript/Reference/Global_Objects/Int8Array
---
<div>{{JSRef}}</div>

<p><strong><code>Int8Array</code></strong> 类型数组表示二进制补码8位有符号整数的数组。内容初始化为0。 一旦建立，你可以使用对象的方法引用数组中的元素，或使用标准数组索引语法( 即，使用括号注释)。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">new Int8Array(length);
new Int8Array(typedArray);
new Int8Array(object);
new Int8Array(buffer [, byteOffset [, length]]);</pre>

<p>有关构造函数语法和参数的更多信息，请访问 <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", "Int8Array.BYTES_PER_ELEMENT")}}</dt>
 <dd>返回数组中每个元素的大小. 在<code>Int8Array中这个值为1</code>.</dd>
 <dt>Int8Array.length</dt>
 <dd>此属性为固定值属性，值为3.查看 {{jsxref("TypedArray.prototype.length", "Int8Array.prototype.length")}}获得获取数组内元素个数方法。</dd>
 <dt>{{jsxref("TypedArray.name", "Int8Array.name")}}</dt>
 <dd>返回构造器方法名称.在Int8Array类型中此值为 "Int8Array"。</dd>
 <dt>{{jsxref("TypedArray.prototype", "Int8Array.prototype")}}</dt>
 <dd><em>TypedArray</em> 对象的构造原型。</dd>
</dl>

<h2 id="方法">方法</h2>

<dl>
 <dt>{{jsxref("TypedArray.from", "Int8Array.from()")}}</dt>
 <dd>从类数组对象或迭代器生成int8Array数组对象. 参照{{jsxref("Array.from()")}}.</dd>
 <dt>{{jsxref("TypedArray.of", "Int8Array.of()")}}</dt>
 <dd>以多个参数构造Int8Array对象， 参照 {{jsxref("Array.of()")}}.</dd>
</dl>

<h2 id="Int8Array_原型方法"><code>Int8Array</code> 原型方法</h2>

<p>所有<strong> Int8Array</strong>对象都继承自 {{jsxref("TypedArray.prototype", "%TypedArray%.prototype")}}.</p>

<h3 id="属性_2">属性</h3>

<dl>
 <dt><code>Int8Array.prototype.constructor</code></dt>
 <dd>这个方法会返回对象的构造原型. 默认为<code>Int8Array构造函数</code>.</dd>
 <dt>{{jsxref("TypedArray.prototype.buffer", "Int8Array.prototype.buffer")}} {{readonlyInline}}</dt>
 <dd>Returns the {{jsxref("ArrayBuffer")}} referenced by the <code>Int8Array</code> Fixed at construction time and thus <strong>read only</strong>.</dd>
 <dt>{{jsxref("TypedArray.prototype.byteLength", "Int8Array.prototype.byteLength")}} {{readonlyInline}}</dt>
 <dd>Returns the length (in bytes) of the <code>Int8Array</code> from the start of its {{jsxref("ArrayBuffer")}}. Fixed at construction time and thus <strong>read only.</strong></dd>
 <dt>{{jsxref("TypedArray.prototype.byteOffset", "Int8Array.prototype.byteOffset")}} {{readonlyInline}}</dt>
 <dd>Returns the offset (in bytes) of the <code>Int8Array</code> from the start of its {{jsxref("ArrayBuffer")}}. Fixed at construction time and thus <strong>read only.</strong></dd>
 <dt>{{jsxref("TypedArray.prototype.length", "Int8Array.prototype.length")}} {{readonlyInline}}</dt>
 <dd>Returns the number of elements hold in the <code>Int8Array</code>. Fixed at construction time and thus <strong>read only.</strong></dd>
</dl>

<h3 id="方法_2">方法</h3>

<dl>
 <dt>{{jsxref("TypedArray.copyWithin", "Int8Array.prototype.copyWithin()")}}</dt>
 <dd>Copies a sequence of array elements within the array. See also {{jsxref("Array.prototype.copyWithin()")}}.</dd>
 <dt>{{jsxref("TypedArray.entries", "Int8Array.prototype.entries()")}}</dt>
 <dd>Returns a new <code>Array Iterator</code> object that contains the key/value pairs for each index in the array. See also {{jsxref("Array.prototype.entries()")}}.</dd>
 <dt>{{jsxref("TypedArray.every", "Int8Array.prototype.every()")}}</dt>
 <dd>Tests whether all elements in the array pass the test provided by a function. See also {{jsxref("Array.prototype.every()")}}.</dd>
 <dt>{{jsxref("TypedArray.fill", "Int8Array.prototype.fill()")}}</dt>
 <dd>Fills all the elements of an array from a start index to an end index with a static value. See also {{jsxref("Array.prototype.fill()")}}.</dd>
 <dt>{{jsxref("TypedArray.filter", "Int8Array.prototype.filter()")}}</dt>
 <dd>Creates a new array with all of the elements of this array for which the provided filtering function returns true. See also {{jsxref("Array.prototype.filter()")}}.</dd>
 <dt>{{jsxref("TypedArray.find", "Int8Array.prototype.find()")}}</dt>
 <dd>Returns the found value in the array, if an element in the array satisfies the provided testing function or <code>undefined</code> if not found. See also {{jsxref("Array.prototype.find()")}}.</dd>
 <dt>{{jsxref("TypedArray.findIndex", "Int8Array.prototype.findIndex()")}}</dt>
 <dd>Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found. See also {{jsxref("Array.prototype.findIndex()")}}.</dd>
 <dt>{{jsxref("TypedArray.forEach", "Int8Array.prototype.forEach()")}}</dt>
 <dd>Calls a function for each element in the array. See also {{jsxref("Array.prototype.forEach()")}}.</dd>
 <dt>{{jsxref("TypedArray.includes", "Int8Array.prototype.includes()")}} {{experimental_inline}}</dt>
 <dd>Determines whether a typed array includes a certain element, returning <code>true</code> or <code>false</code> as appropriate. See also {{jsxref("Array.prototype.includes()")}}.</dd>
 <dt>{{jsxref("TypedArray.indexOf", "Int8Array.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", "Int8Array.prototype.join()")}}</dt>
 <dd>Joins all elements of an array into a string. See also {{jsxref("Array.prototype.join()")}}.</dd>
 <dt>{{jsxref("TypedArray.keys", "Int8Array.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", "Int8Array.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", "Int8Array.prototype.map()")}}</dt>
 <dd>返回一个由回调函数的返回值组成的新数组。. See also {{jsxref("Array.prototype.map()")}}.</dd>
 <dt>{{jsxref("TypedArray.move", "Int8Array.prototype.move()")}} {{non-standard_inline}} {{unimplemented_inline}}</dt>
 <dd>{{jsxref("TypedArray.copyWithin", "Int8Array.prototype.copyWithin()")}} 早期的不标准定义。</dd>
 <dt>{{jsxref("TypedArray.reduce", "Int8Array.prototype.reduce()")}}</dt>
 <dd>从左到右为每个数组元素执行一次回调函数，并把上次回调函数的返回值放在一个暂存器中传给下次回调函数，并返回最后一次回调函数的返回值。参照 {{jsxref("Array.prototype.reduce()")}}.</dd>
 <dt>{{jsxref("TypedArray.reduceRight", "Int8Array.prototype.reduceRight()")}}</dt>
 <dd>从右到左为每个数组元素执行一次回调函数，并把上次回调函数的返回值放在一个暂存器中传给下次回调函数，并返回最后一次回调函数的返回值。参照 {{jsxref("Array.prototype.reduceRight()")}}.</dd>
 <dt>{{jsxref("TypedArray.reverse", "Int8Array.prototype.reverse()")}}</dt>
 <dd>颠倒数组中元素的排列顺序，即原先的第一个变为最后一个，原先的最后一个变为第一个。参照{{jsxref("Array.prototype.reverse()")}}.</dd>
 <dt>{{jsxref("TypedArray.set", "Int8Array.prototype.set()")}}</dt>
 <dd>Stores multiple values in the typed array, reading input values from a specified array.</dd>
 <dt>{{jsxref("TypedArray.slice", "Int8Array.prototype.slice()")}}</dt>
 <dd>抽取当前数组中的一段元素组合成一个新数组。参照{{jsxref("Array.prototype.slice()")}}.</dd>
 <dt>{{jsxref("TypedArray.some", "Int8Array.prototype.some()")}}</dt>
 <dd>如果数组中至少有一个元素满足测试函数，则返回 true，否则返回 false。参照 {{jsxref("Array.prototype.some()")}}.</dd>
 <dt>{{jsxref("TypedArray.sort", "Int8Array.prototype.sort()")}}</dt>
 <dd>对数组元素进行排序，并返回当前数组. 参照{{jsxref("Array.prototype.sort()")}}.</dd>
 <dt>{{jsxref("TypedArray.subarray", "Int8Array.prototype.subarray()")}}</dt>
 <dd>返回一个以给定的初始结束位置裁剪的Int8Array数组.</dd>
 <dt>{{jsxref("TypedArray.values", "Int8Array.prototype.values()")}}</dt>
 <dd>返回一个数组迭代器对象，该迭代器会包含所有数组元素的值。. 参照 {{jsxref("Array.prototype.values()")}}.</dd>
 <dt>{{jsxref("TypedArray.toLocaleString", "Int8Array.prototype.toLocaleString()")}}</dt>
 <dd>返回一个由所有数组元素组合而成的本地化后的字符串. See also {{jsxref("Array.prototype.toLocaleString()")}}.</dd>
 <dt>{{jsxref("TypedArray.toString", "Int8Array.prototype.toString()")}}</dt>
 <dd>返回一个由所有数组元素组合而成的字符串.参照 {{jsxref("Array.prototype.toString()")}}.</dd>
 <dt>{{jsxref("TypedArray.@@iterator", "Int8Array.prototype[@@iterator]()")}}</dt>
 <dd>此方法返回一个带有数组内所有元素的迭代器对象，同Int8Array.prototype.values 。</dd>
</dl>

<h2 id="示例">示例</h2>

<pre class="brush: js">// 以长度参数构造对象
var int8 = new Int8Array(2);
int8[0] = 42;
console.log(int8[0]); // 42
console.log(int8.length); // 2
console.log(int8.BYTES_PER_ELEMENT); // 1

// 以数组构造对象
var arr = new Int8Array([21,31]);
console.log(arr[1]); // 31

// 从另一数组构造对象
var x = new Int8Array([21, 31]);
var y = new Int8Array(x);
console.log(y[0]); // 21

// 从ArrayBuffer构造对象
var buffer = new ArrayBuffer(8);
var z = new Int8Array(buffer, 1, 4);
</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">评论</th>
  </tr>
  <tr>
   <td>{{SpecName('Typed Array')}}</td>
   <td>{{Spec2('Typed Array')}}</td>
   <td>已被 ECMAScript 6取代。</td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#table-49', 'TypedArray constructors')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>ECMA 标准中构造对象时 new 关键字为必需。</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>功能</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>7.0</td>
   <td>{{ CompatGeckoDesktop("2") }}</td>
   <td>10</td>
   <td>11.6</td>
   <td>5.1</td>
  </tr>
  <tr>
   <td><code>new</code> is required</td>
   <td>{{CompatUnknown}}</td>
   <td>{{ CompatGeckoDesktop("44") }}</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>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>4.0</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{ CompatGeckoMobile("2") }}</td>
   <td>10</td>
   <td>11.6</td>
   <td>4.2</td>
  </tr>
  <tr>
   <td><code>new</code> is required</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{ CompatGeckoMobile("44") }}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="兼容性说明">兼容性说明</h2>

<p>自 ECMAScript 2015 (ES6)施行, <code>Int8Array</code> 需要使用{{jsxref("Operators/new", "new")}} 构造. 从当前版本开始，不加new而便调用<code>Int8Array</code> 构造器方法, 将报出 {{jsxref("TypeError")}} 错误.</p>

<pre class="brush: js example-bad">var dv = Int8Array([1, 2, 3]);
// TypeError: calling a builtin Int8Array constructor
// without new is forbidden</pre>

<pre class="brush: js example-good">var dv = new Int8Array([1, 2, 3]);</pre>

<h2 id="相关链接">相关链接</h2>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Typed_arrays" title="en/JavaScript typed arrays">JavaScript typed arrays</a></li>
 <li>{{jsxref("ArrayBuffer")}}</li>
 <li>{{jsxref("DataView")}}</li>
</ul>