--- title: 按位与 (&) slug: Web/JavaScript/Reference/Operators/Bitwise_AND translation_of: Web/JavaScript/Reference/Operators/Bitwise_AND original_slug: Web/JavaScript/Reference/Operators/按位与 --- <div>{{jsSidebar("Operators")}}</div> <p>按位与运算符 (<code>&</code>) 在每个位上返回 <code>1</code> ,这两个操作数对应的位都是 <code>1</code>.</p> <div>{{EmbedInteractiveExample("pages/js/expressions-bitwise-and.html")}}</div> <div class="hidden">The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone <a href="https://github.com/mdn/interactive-examples">https://github.com/mdn/interactive-examples</a> and send us a pull request.</div> <h2 id="语法">语法</h2> <pre class="syntaxbox notranslate"><code><var>a</var> & <var>b</var></code> </pre> <h2 id="描述">描述</h2> <p>操作数被转换为32位整数,并由一系列位(0和1)表示。 超过32位的数字将丢弃其最高有效位。 例如,以下大于32位的整数将被转换为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>与运算的真值表:</p> <table class="standard-table"> <thead> <tr> <th class="header" scope="col">a</th> <th class="header" scope="col">b</th> <th class="header" scope="col">a AND b</th> </tr> </thead> <tbody> <tr> <td>0</td> <td>0</td> <td>0</td> </tr> <tr> <td>0</td> <td>1</td> <td>0</td> </tr> <tr> <td>1</td> <td>0</td> <td>0</td> </tr> <tr> <td>1</td> <td>1</td> <td>1</td> </tr> </tbody> </table> <pre class="brush: js notranslate">. 9 (base 10) = 00000000000000000000000000001001 (base 2) 14 (base 10) = 00000000000000000000000000001110 (base 2) -------------------------------- 14 & 9 (base 10) = 00000000000000000000000000001000 (base 2) = 8 (base 10) </pre> <p>将任何数字<code>x</code>与<code>0</code>进行按位与运算将得出<code>0</code>。</p> <h2 id="示例">示例</h2> <h3 id="使用按位与">使用按位与</h3> <pre class="brush: js notranslate">// 5: 00000000000000000000000000000101 // 2: 00000000000000000000000000000010 5 & 2; // 0</pre> <h2 id="规范说明">规范说明</h2> <table class="standard-table"> <thead> <tr> <th scope="col">Specification</th> </tr> </thead> <tbody> <tr> <td>{{SpecName('ESDraft', '#prod-BitwiseANDExpression', 'Bitwise AND 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_and")}}</p> <h2 id="参阅">参阅</h2> <ul> <li><a href="/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Bitwise">Bitwise operators in the JS guide</a></li> <li><a href="/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_AND_assignment">Bitwise AND assignment operator</a></li> </ul>