---
title: 按位非 (~)
slug: Web/JavaScript/Reference/Operators/Bitwise_NOT
tags:
  - JavaScript
  - 位操作符
  - 操作符
translation_of: Web/JavaScript/Reference/Operators/Bitwise_NOT
---
<div>{{jsSidebar("Operators")}}</div>

<p>按位非运算符（~），反转操作数的位。</p>

<div>{{EmbedInteractiveExample("pages/js/expressions-bitwise-not.html")}}</div>

<div></div>



<h2 id="语法">语法</h2>

<pre class="syntaxbox notranslate"><code><var>~a</var></code>
</pre>

<h2 id="描述">描述</h2>

<p>操作数被转换为32位二进制表示（0和1）。超过32位的数字将丢弃其最高有效位。如下例子中，超过32位的整数转换为32位整数：</p>

<pre class="brush: js notranslate">Before: 11100110111110100000000000000110000000000001
After:              10100000000000000110000000000001</pre>

<p>第一个操作数中的每个位都与第二个操作数中的相应位配对：第一位到第一位，第二位到第二位，依此类推。</p>

<p>将运算符应用于每对位，然后按位构造结果。</p>

<p>非运算的真值表:</p>

<table class="standard-table">
 <thead>
  <tr>
   <th class="header" scope="col">a</th>
   <th class="header" scope="col">NOT a</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>0</td>
   <td>1</td>
  </tr>
  <tr>
   <td>1</td>
   <td>0</td>
  </tr>
 </tbody>
</table>

<pre class="brush: js notranslate"> 9 (base 10) = 00000000000000000000000000001001 (base 2)
               --------------------------------
~9 (base 10) = 11111111111111111111111111110110 (base 2) = -10 (base 10)
</pre>

<p>按位非运算时，任何数字<code>x的运算结果都是</code><code>-(x + 1)</code>。例如，<code>〜-5</code>运算结果为<code>4</code>。</p>

<p>Note that due to using 32-bit representation for numbers both <code>~-1</code> and <code>~4294967295</code> (2<sup>32</sup>-1) results in <code>0</code>.</p>

<p>请注意，由于对数字<code>~-1</code>和<code>~4294967295</code> (2<sup>32</sup>-1) 使用32位表示形式，结果均为0。</p>

<h2 id="例子">例子</h2>

<h3 id="使用按位取反">使用按位取反</h3>

<pre class="brush: js notranslate">~0;  // -1
~-1; // 0
~1;  // -2
</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-unary-operators', 'Unary NOT expression')}}</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>



<p>{{Compat("javascript.operators.bitwise_not")}}</p>

<h2 id="参见">参见</h2>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Bitwise">Bitwise operators in the JS guide</a></li>
</ul>