---
title: DataView.prototype.byteLength
slug: Web/JavaScript/Reference/Global_Objects/DataView/byteLength
translation_of: Web/JavaScript/Reference/Global_Objects/DataView/byteLength
---
<div>{{JSRef}}</div>

<p> <strong><code>byteLength</code></strong> 属性描述了视图从它的 {{jsxref("ArrayBuffer")}} 开始的字节长度。</p>

<div>{{EmbedInteractiveExample("pages/js/dataview-bytelength.html")}}</div>



<h2 id="语法">语法</h2>

<pre class="syntaxbox"><var>dataview</var>.byteLength</pre>

<h2 id="描述">描述</h2>

<p><code>byteLength</code> 属性是一个获取(accessor)属性，它的 set 属性为 undefined，这意味着它是只读的。值在 <code>DataView 被创建时就确定了，且不能改变。如果</code> <code>DataView</code> 没有指定偏移量或byteLength，那么被引用的 <code>ArrayBuffer 的字节长度将被返回。</code></p>

<h2 id="Examples">Examples</h2>

<h3 id="Using_the_byteLength_property">Using the <code>byteLength</code> property</h3>

<pre class="brush:js">var buffer = new ArrayBuffer(8);
var dataview = new DataView(buffer);
dataview.byteLength; // 8 (matches the byteLength of the buffer)

var dataview2 = new DataView(buffer, 1, 5);
dataview2.byteLength; // 5 (as specified when constructing the DataView)

var dataview3 = new DataView(buffer, 2);
dataview3.byteLength; // 6 (due to the offset of the constructed DataView)
</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-get-dataview.prototype.bytelength', 'DataView.prototype.byteLength')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-get-dataview.prototype.bytelength', 'DataView.prototype.byteLength')}}</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.DataView.byteLength")}}</p>

<h2 id="相关链接">相关链接</h2>

<ul>
 <li>{{jsxref("DataView")}}</li>
 <li>{{jsxref("ArrayBuffer")}}</li>
</ul>