path: root/files/zh-tw/web/javascript/reference/global_objects/arraybuffer/index.html

---
title: ArrayBuffer
slug: Web/JavaScript/Reference/Global_Objects/ArrayBuffer
translation_of: Web/JavaScript/Reference/Global_Objects/ArrayBuffer
---
<p>{{JSRef}}</p>

<p><strong><code>ArrayBuffer</code></strong> 物件是一種表示通用、固定大小的原始二進制資料緩衝。想要直接操作一個 <code>ArrayBuffer</code> 物件的內容是不可能的。若要讀寫該緩衝的內容則必須透過視圖，可以選擇建立一個 {{jsxref("DataView")}} 視圖物件或是一個限定其成員為某種型別的 {{jsxref("TypedArray")}} 視圖物件，它們皆能以特定的型別解讀、修改 <code>ArrayBuffer</code>。</p>

<h2 id="語法">語法</h2>

<pre class="syntaxbox">new ArrayBuffer(length)
</pre>

<h3 id="參數">參數</h3>

<dl>
 <dt><code>length</code></dt>
 <dd>要建立的緩衝陣列大小，以位元組（byte）計算。</dd>
</dl>

<h3 id="回傳值">回傳值</h3>

<p>為一個新建立的指定大小 <code>ArrayBuffer</code> 物件，其內容皆初始化為 0。</p>

<h3 id="Exceptions">Exceptions</h3>

<p>A {{jsxref("RangeError")}} is thrown if the <code>length</code> is larger than {{jsxref("Number.MAX_SAFE_INTEGER")}} (&gt;= 2 ** 53) or negative.</p>

<h2 id="說明">說明</h2>

<p>The <code>ArrayBuffer</code> constructor creates a new <code>ArrayBuffer</code> of the given length in bytes.</p>

<h3 id="從既有的資料取得_ArrayBuffer">從既有的資料取得 ArrayBuffer</h3>

<ul>
 <li><a href="/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding#Appendix.3A_Decode_a_Base64_string_to_Uint8Array_or_ArrayBuffer">From a Base64 string</a></li>
 <li><a href="/zh-TW/docs/Web/API/FileReader#readAsArrayBuffer()">從本地端檔案</a></li>
</ul>

<h2 id="屬性">屬性</h2>

<dl>
 <dt><code>ArrayBuffer.length</code></dt>
 <dd>The <code>ArrayBuffer</code> constructor's length property whose value is 1.</dd>
 <dt>{{jsxref("ArrayBuffer.@@species", "get ArrayBuffer[@@species]")}}</dt>
 <dd>The constructor function that is used to create derived objects.</dd>
 <dt>{{jsxref("ArrayBuffer.prototype")}}</dt>
 <dd>Allows the addition of properties to all <code>ArrayBuffer</code> objects.</dd>
</dl>

<h2 id="方法">方法</h2>

<dl>
 <dt>{{jsxref("ArrayBuffer.isView", "ArrayBuffer.isView(arg)")}}</dt>
 <dd>Returns <code>true</code> if <code>arg</code> is one of the ArrayBuffer views, such as <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray">typed array objects</a> or a {{jsxref("DataView")}}. Returns <code>false</code> otherwise.</dd>
 <dt>{{jsxref("ArrayBuffer.transfer", "ArrayBuffer.transfer(oldBuffer [, newByteLength])")}} {{experimental_inline}}</dt>
 <dd>
 <div class="line" id="file-arraybuffer-transfer-LC6">Returns a new <code>ArrayBuffer</code> whose contents are taken from the <code>oldBuffer</code>'s data and then is either truncated or zero-extended by <code>newByteLength</code>.</div>
 </dd>
</dl>

<h2 id="ArrayBuffer_實例"><code>ArrayBuffer</code> 實例</h2>

<p>所有的 <code>ArrayBuffer</code> 物件實例皆繼承自 {{jsxref("ArrayBuffer.prototype")}}.</p>

<h3 id="屬性_2">屬性</h3>

<p>{{page('zh-TW/Web/JavaScript/JavaScript_typed_arrays/ArrayBuffer/prototype','屬性')}}</p>

<h3 id="方法_2">方法</h3>

<p>{{page('/zh-TW/docs/Web/JavaScript/JavaScript_typed_arrays/ArrayBuffer/prototype','方法')}}</p>

<dl>
 <dt>{{jsxref("ArrayBuffer.slice()")}} {{non-standard_inline}}</dt>
 <dd>Has the same functionality as {{jsxref("ArrayBuffer.prototype.slice()")}}.</dd>
</dl>

<h2 id="範例">範例</h2>

<p>In this example, we create a 8-byte buffer with a {{jsxref("Global_Objects/Int32Array", "Int32Array")}} view referring to the buffer:</p>

<pre class="brush: js">var buffer = new ArrayBuffer(8);
var view   = new Int32Array(buffer);</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('Typed Array')}}</td>
   <td>{{Spec2('Typed Array')}}</td>
   <td>Superseded by ECMAScript 6.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-arraybuffer-constructor', 'ArrayBuffer')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition in an ECMA standard. Specified that <code>new</code> is required.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-arraybuffer-constructor', 'ArrayBuffer')}}</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>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Edge</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>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoDesktop("2")}}</td>
   <td>10</td>
   <td>11.6</td>
   <td>5.1</td>
  </tr>
  <tr>
   <td><code>ArrayBuffer()</code> without <code>new</code> throws</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatGeckoDesktop("44")}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
  <tr>
   <td><code>ArrayBuffer.slice()</code> {{non-standard_inline}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}<br>
    {{CompatNo}} {{CompatGeckoDesktop("53")}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</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>Edge</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>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoMobile("2")}}</td>
   <td>10</td>
   <td>11.6</td>
   <td>4.2</td>
  </tr>
  <tr>
   <td><code>ArrayBuffer()</code> without <code>new</code> throws</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatGeckoMobile("44")}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
  <tr>
   <td><code>ArrayBuffer.slice()</code> {{non-standard_inline}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}<br>
    {{CompatNo}} {{CompatGeckoMobile("53")}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="相容性備註">相容性備註</h2>

<p>Starting with ECMAScript 2015, <code>ArrayBuffer</code> constructors require to be constructed with a {{jsxref("Operators/new", "new")}} operator. Calling an <code>ArrayBuffer</code> constructor as a function without <code>new</code>, will throw a {{jsxref("TypeError")}} from now on.</p>

<pre class="brush: js example-bad">var dv = ArrayBuffer(10);
// TypeError: calling a builtin ArrayBuffer constructor
// without new is forbidden</pre>

<pre class="brush: js example-good">var dv = new ArrayBuffer(10);</pre>

<h2 id="參見">參見</h2>

<ul>
 <li>{{jsxref("TypedArray")}}</li>
 <li>{{jsxref("SharedArrayBuffer")}}</li>
</ul>