---
title: DataView.prototype.getFloat64()
slug: Web/JavaScript/Reference/Global_Objects/DataView/getFloat64
translation_of: Web/JavaScript/Reference/Global_Objects/DataView/getFloat64
---
<div>{{JSRef}}</div>

<p><strong><code>getFloat64()</code></strong><code>方法</code><code>从</code><a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/DataView" title="DataView 视图提供了一种用于向 ArrayBuffer 读写数据的底层接口。"><code>DataView</code></a>相对于起始位置偏移 n 个字节处开始，获取一个64-bit数(双精度浮点型，8个字节).</p>

<div>{{EmbedInteractiveExample("pages/js/dataview-getfloat64.html")}}</div>



<h2 id="语法">语法</h2>

<pre class="syntaxbox"><var>dataview</var>.getFloat64(byteOffset [, littleEndian])</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt>byteOffset</dt>
 <dd>偏移量, 单位为字节, 从头开始计算.</dd>
 <dt>littleEndian</dt>
 <dd>{{optional_inline}} Indicates whether the 64-bit float is stored in {{Glossary("Endianness", "little- or big-endian")}} format. If false or undefined, a big-endian value is read.</dd>
</dl>

<h3 id="返回">返回</h3>

<p>一个双精度浮点型64位数.</p>

<h3 id="抛出错误">抛出错误</h3>

<dl>
 <dt>{{jsxref("RangeError")}}</dt>
 <dd>如果byteOffset超出了视图能储存的值，就会抛出错误.</dd>
</dl>

<h2 id="描述">描述</h2>

<p>没有对齐约束; 多字节值可以从任何偏移量获取.</p>

<h2 id="例子">例子</h2>

<pre class="brush:js">var buffer = new ArrayBuffer(8);
var dataview = new DataView(buffer);
dataview.getFloat64(1); // 0
</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('Typed Array')}}</td>
   <td>{{Spec2('Typed Array')}}</td>
   <td>Superseded by ECMAScript 6.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-dataview.prototype.getfloat64', 'DataView.prototype.getFloat64')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition in ECMA standard.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-dataview.prototype.getfloat64', 'DataView.prototype.getFloat64')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td></td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器支持">浏览器支持</h2>



<p>{{Compat("javascript.builtins.DataView.getFloat64")}}</p>

<h2 id="另见">另见</h2>

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