---
title: Math.SQRT2
slug: Web/JavaScript/Reference/Global_Objects/Math/SQRT2
translation_of: Web/JavaScript/Reference/Global_Objects/Math/SQRT2
---
<p>{{JSRef("Global_Objects", "Math")}}</p>
<h2 id="Summary" name="Summary">概述</h2>
<p><code><strong>Math.SQRT2</strong></code> 属性表示 2 的平方根，约为 1.414：</p>
<h2 id="Description" name="Description">描述</h2>
<p>由于 <code>SQRT2</code> 是 <code>Math</code> 的静态属性，所以应该像这样使用：<code>Math.SQRT2</code>，而不是作为你创建的 <code>Math</code> 实例的属性（<code>Math</code> 不是构造函数）。</p>
<h2 id="Examples" name="Examples">示例</h2>
<h3 id="Example:_Using_Math.SQRT2" name="Example:_Using_Math.SQRT2">例子：使用 <code>Math.SQRT2</code></h3>
<p>下面的函数返回 2 的平方根：</p>
<pre class="brush:js">function getRoot2() {
   return Math.SQRT2;
}

getRoot2(); // 1.4142135623730951</pre>
<h2 id="规范" style="margin-bottom: 20px; line-height: 30px;">规范</h2>
<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">规范版本</th>
   <th scope="col">规范状态</th>
   <th scope="col">注解</th>
  </tr>
  <tr>
   <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td>
   <td>Standard</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES5.1', '#sec-15.8.1.8', 'Math.SQRT2')}}</td>
   <td>{{Spec2('ES5.1')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-math.sqrt2', 'Math.SQRT2')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>
<h2 id="浏览器兼容性" style="margin-bottom: 20px; line-height: 30px;">浏览器兼容性</h2>
<p>{{ CompatibilityTable() }}</p>
<div id="compat-desktop">
 <table class="compat-table">
  <tbody>
   <tr>
    <th style="line-height: 16px;">Feature</th>
    <th style="line-height: 16px;">Chrome</th>
    <th style="line-height: 16px;">Firefox (Gecko)</th>
    <th style="line-height: 16px;">Internet Explorer</th>
    <th style="line-height: 16px;">Opera</th>
    <th style="line-height: 16px;">Safari</th>
   </tr>
   <tr>
    <td>Basic support</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
   </tr>
  </tbody>
 </table>
</div>
<div id="compat-mobile">
 <table class="compat-table">
  <tbody>
   <tr>
    <th style="line-height: 16px;">Feature</th>
    <th style="line-height: 16px;">Android</th>
    <th style="line-height: 16px;">Chrome for Android</th>
    <th style="line-height: 16px;">Firefox Mobile (Gecko)</th>
    <th style="line-height: 16px;">IE Mobile</th>
    <th style="line-height: 16px;">Opera Mobile</th>
    <th style="line-height: 16px;">Safari Mobile</th>
   </tr>
   <tr>
    <td>Basic support</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
   </tr>
  </tbody>
 </table>
</div>
<h2 id="See_also" name="See_also" style="margin-bottom: 20px; line-height: 30px;">相关链接</h2>
<ul>
 <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li>
</ul>
<p></p>