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640 lines
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640 lines
34 KiB
HTML
<article id="wikiArticle">
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<div></div>
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<h2 id="Summary" name="Summary">概述</h2>
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<p><strong>按位操作符（Bitwise operators）</strong> 将其操作数（operands）当作32位的比特序列（由0和1组成），而不是十进制、十六进制或八进制<a href="Reference/Global_Objects/Number" title="/en-US/docs/JavaScript/Reference/Global_Objects/Number">数值</a>。例如，十进制数9，用二进制表示则为1001。按位操作符操作数字的二进制形式，但是返回值依然是标准的JavaScript数值。</p>
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<p>下面的表格总结了JavaScript中的按位操作符：</p>
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<table class="standard-table">
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<tbody>
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<tr>
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<th>运算符</th>
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<th>用法</th>
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<th>描述</th>
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</tr>
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<tr>
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<td><a href="#Bitwise_AND">按位与（ AND）</a></td>
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<td style="white-space: nowrap;"><code>a & b</code></td>
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<td>对于每一个比特位，只有两个操作数相应的比特位都是1时，结果才为1，否则为0。</td>
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</tr>
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<tr>
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<td><a href="#Bitwise_OR">按位或（OR）</a></td>
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<td style="white-space: nowrap;"><code>a | b</code></td>
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<td>对于每一个比特位，当两个操作数相应的比特位至少有一个1时，结果为1，否则为0。</td>
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</tr>
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<tr>
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<td><a href="#Bitwise_XOR">按位异或（XOR）</a></td>
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<td style="white-space: nowrap;"><code>a ^ b</code></td>
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<td>对于每一个比特位，当两个操作数相应的比特位有且只有一个1时，结果为1，否则为0。</td>
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</tr>
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<tr>
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<td><a href="#Bitwise_NOT">按位非（NOT）</a></td>
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<td style="white-space: nowrap;"><code>~ a</code></td>
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<td>反转操作数的比特位，即0变成1，1变成0。</td>
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</tr>
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<tr>
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<td><a href="#Left_shift">左移（L</a><a href="#Left_shift" style="line-height: 1.5;">eft shift）</a></td>
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<td style="white-space: nowrap;"><code>a << b</code></td>
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<td>将 <code>a</code> 的二进制形式向左移 <code>b</code> (< 32) 比特位，右边用0填充。</td>
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</tr>
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<tr>
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<td><a href="#Right_shift">有符号右移</a></td>
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<td style="white-space: nowrap;"><code>a >> b</code></td>
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<td>将 a 的二进制表示向右移<code> b </code>(< 32) 位，丢弃被移出的位。</td>
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</tr>
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<tr>
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<td><a href="#Unsigned_right_shift">无符号右移</a></td>
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<td style="white-space: nowrap;"><code>a >>> b</code></td>
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<td>将 a 的二进制表示向右移<code> b </code>(< 32) 位，丢弃被移出的位，并使用 0 在左侧填充。</td>
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</tr>
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</tbody>
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</table>
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<h2 id="有符号32位整数">有符号32位整数</h2>
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<p>所有的按位操作符的操作数都会被转成补码（two's complement）形式的有符号32位整数。补码形式是指一个数的负对应值（negative counterpart）（如 5和-5）为数值的所有比特位反转后，再加1。反转比特位即该数值进行’非‘位运算，也即该数值的反码。例如下面为整数314的二进制编码：</p>
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<pre>00000000000000000000000100111010
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</code></pre>
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<p>下面编码 <code>~314</code>，即 <code>314</code> 的反码：</p>
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<pre>11111111111111111111111011000101
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</code></pre>
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<p>最后，下面编码 <code>-314</code>，即 <code>314</code> 的补码：</p>
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<pre>11111111111111111111111011000110
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</code></pre>
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<p>补码保证了当一个数是正数时，其最左的比特位是0，当一个数是负数时，其最左的比特位是1。因此，最左边的比特位被称为符号位（<em>sign bit</em>）。</p>
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<p><code>0</code> 是所有比特数字0组成的整数。</p>
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<pre>0 (base 10) = 00000000000000000000000000000000 (base 2)
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</code></pre>
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<p><code>-1</code> 是所有比特数字1组成的整数。</p>
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<pre>-1 (base 10) = 11111111111111111111111111111111 (base 2)
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</code></pre>
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<p><code>-2147483648</code>（十六进制形式：<code>-0x80000000</code>）是除了最左边为1外，其他比特位都为0的整数。</p>
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<pre>-2147483648 (base 10) = 10000000000000000000000000000000 (base 2)
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</code></pre>
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<p><code>2147483647</code>（十六进制形式：<code>0x7fffffff</code>）是除了最左边为0外，其他比特位都为1的整数。</p>
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<pre>2147483647 (base 10) = 01111111111111111111111111111111 (base 2)
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</code></pre>
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<p>数字<code>-2147483648</code> 和 <code>2147483647</code> 是32位有符号数字所能表示的最小和最大整数。</p>
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<h2 id="按位逻辑操作符">按位逻辑操作符</h2>
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<p>从概念上讲，按位逻辑操作符按遵守下面规则：</p>
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<ul>
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<li>操作数被转换成32位整数，用比特序列（0和1组成）表示。超过32位的数字会被丢弃。<br/>
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例如, 以下具有32位以上的整数将转换为32位整数:</li>
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<li>
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<pre>转换前: 11100110111110100000000000000110000000000001
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转换后: 10100000000000000110000000000001</code></pre>
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</li>
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<li>第一个操作数的每个比特位与第二个操作数的相应比特位匹配：第一位对应第一位，第二位对应第二位，以此类推。</li>
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<li>位运算符应用到每对比特位，结果是新的比特值。</li>
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</ul>
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<h3 id="(按位与)"><a name="Bitwise_AND">& (按位与)</a></h3>
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<p>对每对比特位执行<strong>与（AND）操作</strong>。只有 a 和 b 都是 1 时，a AND b 才是 1。<strong>与操作</strong>的真值表如下：</p>
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<table class="standard-table">
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<tbody>
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<tr>
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<td class="header">a</td>
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<td class="header">b</td>
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<td class="header">a AND b</td>
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</tr>
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<tr>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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</tr>
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<tr>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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</tr>
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<tr>
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<td>1</td>
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<td>0</td>
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<td>0</td>
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</tr>
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<tr>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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</tr>
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</tbody>
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</table>
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<pre> 9 (base 10) = 00000000000000000000000000001001 (base 2)
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14 (base 10) = 00000000000000000000000000001110 (base 2)
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--------------------------------
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14 & 9 (base 10) = 00000000000000000000000000001000 (base 2) = 8 (base 10)
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</code></pre>
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<p>将任一数值 x 与 0 执行按位与操作，其结果都为 0。将任一数值 x 与 -1 执行按位与操作，其结果都为 x。</p>
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<h3 id="(按位或)"><a name="Bitwise_OR">| (按位或)</a></h3>
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<p>对每一对比特位执行<strong>或（OR）操作</strong>。如果 a 或 b 为 1，则 <code>a</code> OR <code>b</code> 结果为 1。<strong>或操作</strong>的真值表：</p>
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<table class="standard-table">
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<tbody>
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<tr>
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<td class="header">a</td>
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<td class="header">b</td>
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<td class="header">a OR b</td>
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</tr>
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<tr>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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</tr>
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<tr>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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</tr>
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<tr>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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</tr>
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<tr>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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</tr>
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</tbody>
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</table>
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<pre> 9 (base 10) = 00000000000000000000000000001001 (base 2)
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14 (base 10) = 00000000000000000000000000001110 (base 2)
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--------------------------------
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14 | 9 (base 10) = 00000000000000000000000000001111 (base 2) = 15 (base 10)
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</code></pre>
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<p>将任一数值 x 与 0 进行按位或操作，其结果都是 x。将任一数值 x 与 -1 进行按位或操作，其结果都为 -1。</p>
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<p>补充一些例子：</p>
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<pre><code class="language-javascript">1 | 0 ; // 1
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1.1 | 0 ; // 1
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'asfdasfda' | 0 ; // 0
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0 | 0 ; // 0
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(-1) | 0 ; // -1
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(-1.5646) | 0 ; // -1
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[] | 0 ; // 0
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({}) | 0 ; // 0
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"123456" | 0 ; // 123456
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1.23E2 | 0; // 123
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1.23E12 | 0; // 1639353344
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-1.23E2 | 0; // -123
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-1.23E12 | 0; // -1639353344</code></pre>
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<p> </p>
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<h3 id="(按位异或)"><a name="Bitwise_XOR">^ (按位异或)</a></h3>
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<p>对每一对比特位执行<strong>异或（XOR）操作</strong>。当 a 和 b 不相同时，<code>a</code> XOR <code>b</code> 的结果为 1。<strong>异或操作</strong>真值表：</p>
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<table class="standard-table">
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<tbody>
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<tr>
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<td class="header">a</td>
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<td class="header">b</td>
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<td class="header">a XOR b</td>
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</tr>
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<tr>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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</tr>
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<tr>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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</tr>
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<tr>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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</tr>
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<tr>
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<td>1</td>
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<td>1</td>
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<td>0</td>
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</tr>
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</tbody>
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</table>
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<pre> 9 (base 10) = 00000000000000000000000000001001 (base 2)
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14 (base 10) = 00000000000000000000000000001110 (base 2)
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--------------------------------
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14 ^ 9 (base 10) = 00000000000000000000000000000111 (base 2) = 7 (base 10)
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</code></pre>
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<p>将任一数值 x 与 0 进行异或操作，其结果为 x。将任一数值 x 与 -1 进行异或操作，其结果为 ~x。</p>
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<h3 id="(按位非)"><a name="Bitwise_NOT">~ (按位非)</a></h3>
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<p>对每一个比特位执行<strong>非（NOT）操作</strong>。NOT <code>a</code> 结果为 a 的反转（即反码）。<strong>非操作</strong>的真值表：</p>
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<table class="standard-table">
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<tbody>
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<tr>
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<td class="header">a</td>
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<td class="header">NOT a</td>
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</tr>
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<tr>
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<td>0</td>
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<td>1</td>
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</tr>
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<tr>
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<td>1</td>
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<td>0</td>
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</tr>
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</tbody>
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</table>
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<pre> 9 (base 10) = 00000000000000000000000000001001 (base 2)
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--------------------------------
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~9 (base 10) = 11111111111111111111111111110110 (base 2) = -10 (base 10)
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</code></pre>
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<p>对任一数值 x 进行按位非操作的结果为 -(x + 1)。例如，~5 结果为 -6。</p>
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<p>与 indexOf 一起使用示例：</p>
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<pre><code class="language-javascript">var str = 'rawr';
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var searchFor = 'a';
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// 这是 if (-1*str.indexOf('a') <= 0) 条件判断的另一种方法
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if (~str.indexOf(searchFor)) {
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// searchFor 包含在字符串中
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} else {
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// searchFor 不包含在字符串中
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}
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// (~str.indexOf(searchFor))的返回值
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// r == -1
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// a == -2
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// w == -3
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</code></pre>
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<h2 id="按位移动操作符">按位移动操作符</h2>
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<p>按位移动操作符有两个操作数：第一个是要被移动的数字，而第二个是要移动的长度。移动的方向根据操作符的不同而不同。</p>
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<p>按位移动会先将操作数转换为大端字节序顺序(big-endian order)的32位整数,并返回与左操作数相同类型的结果。右操作数应小于 32位，否则只有最低 5 个字节会被使用。</p>
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<pre>注：Big-Endian:高位字节排放在内存的低地址端，低位字节排放在内存的高地址端，
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又称为"高位编址"。
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Big-Endian是最直观的字节序：
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①把内存地址从左到右按照由低到高的顺序写出；
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②把值按照通常的高位到低位的顺序写出；
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③两者对照，一个字节一个字节的填充进去。</code></pre>
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<h3 id="<<_(左移)"><a name="Left_shift"><< (左移)</a></h3>
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<p>该操作符会将第一个操作数向左移动指定的位数。向左被移出的位被丢弃，右侧用 0 补充。</p>
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<p>For example, <code>9 << 2</code> yields 36:</p>
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<pre> 9 (base 10): 00000000000000000000000000001001 (base 2)
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--------------------------------
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9 << 2 (base 10): 00000000000000000000000000100100 (base 2) = 36 (base 10)
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</code></pre>
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<p>在数字 <strong>x</strong> 上左移 <strong>y</strong> 比特得到 <strong>x * 2<sup>y</sup></strong>.</p>
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<h3 id=">>_(有符号右移)"><a name="Right_shift">>> (有符号右移)</a></h3>
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<p>该操作符会将第一个操作数向右移动指定的位数。向右被移出的位被丢弃，拷贝最左侧的位以填充左侧。由于新的最左侧的位总是和以前相同，符号位没有被改变。所以被称作“符号传播”。</p>
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<p>例如， <code>9 >> 2</code> 得到 2:</p>
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<pre> 9 (base 10): 00000000000000000000000000001001 (base 2)
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--------------------------------
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9 >> 2 (base 10): 00000000000000000000000000000010 (base 2) = 2 (base 10)
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</code></pre>
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<p>相比之下， <code>-9 >> 2</code> 得到 -3，因为符号被保留了。</p>
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<pre> -9 (base 10): 11111111111111111111111111110111 (base 2)
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--------------------------------
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-9 >> 2 (base 10): 11111111111111111111111111111101 (base 2) = -3 (base 10)
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</code></pre>
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<h3 id=">>>_(无符号右移)"><a name="Unsigned_right_shift">>>> (无符号右移)</a></h3>
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<p>该操作符会将第一个操作数向右移动指定的位数。向右被移出的位被丢弃，左侧用0填充。因为符号位变成了 0，所以结果总是非负的。（译注：即便右移 0 个比特，结果也是非负的。）</p>
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<p>对于非负数，有符号右移和无符号右移总是返回相同的结果。例如， <code>9 >>> 2</code> 得到 2 和 <code>9 >> 2</code> 相同：</p>
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<pre> 9 (base 10): 00000000000000000000000000001001 (base 2)
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--------------------------------
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9 >>> 2 (base 10): 00000000000000000000000000000010 (base 2) = 2 (base 10)
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</code></pre>
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<p>但是对于负数却不尽相同。 <code>-9 >>> 2</code> 产生 1073741821 这和 <code>-9 >> 2</code> 不同：</p>
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<pre> -9 (base 10): 11111111111111111111111111110111 (base 2)
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--------------------------------
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-9 >>> 2 (base 10): 00111111111111111111111111111101 (base 2) = 1073741821 (base 10)
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</code></pre>
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<h2 id="示例">示例</h2>
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<h3 id="例子：标志位与掩码">例子：标志位与掩码</h3>
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<p>位运算经常被用来创建、处理以及读取标志位序列——一种类似二进制的变量。虽然可以使用变量代替标志位序列，但是这样可以节省内存（1/32）。</p>
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<p>例如，有 4 个标志位：</p>
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<ul>
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<li>标志位 A：我们有 ant</li>
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<li>标志位 B：我们有 bat</li>
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<li>标志位 C：我们有 cat</li>
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<li>标志位 D：我们有 duck</li>
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</ul>
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<p>标志位通过位序列 DCBA 来表示。当一个位被置位 (set) 时，它的值为 1 。当被清除 (clear) 时，它的值为 0 。例如一个变量 <code>flags</code> 的二进制值为 0101：</p>
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<pre><code class="language-javascript">var flags = 5; // 二进制 0101
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</code></pre>
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<p>这个值表示：</p>
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<ul>
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<li>标志位 A 是 true （我们有 ant）；</li>
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<li>标志位 B 是 false （我们没有 bat）；</li>
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<li>标志位 C 是 true （我们有 cat）；</li>
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<li>标志位 D 是 false （我们没有 duck）；</li>
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</ul>
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<p>因为位运算是 32 位的， 0101 实际上是 00000000000000000000000000000101。因为前面多余的 0 没有任何意义，所以他们可以被忽略。</p>
|
||
<p>掩码 (bitmask) 是一个通过与/或来读取标志位的位序列。典型的定义每个标志位的原语掩码如下：</p>
|
||
<pre><code class="language-javascript">var FLAG_A = 1; // 0001
|
||
var FLAG_B = 2; // 0010
|
||
var FLAG_C = 4; // 0100
|
||
var FLAG_D = 8; // 1000
|
||
</code></pre>
|
||
<p>新的掩码可以在以上掩码上使用逻辑运算创建。例如，掩码 1011 可以通过 FLAG_A、FLAG_B 和 FLAG_D 逻辑或得到：</p>
|
||
<pre><code class="language-javascript">var mask = FLAG_A | FLAG_B | FLAG_D; // 0001 | 0010 | 1000 => 1011
|
||
</code></pre>
|
||
<p>某个特定的位可以通过与掩码做逻辑与运算得到，通过与掩码的与运算可以去掉无关的位，得到特定的位。例如，掩码 0100 可以用来检查标志位 C 是否被置位：</p>
|
||
<pre><code class="language-javascript">// 如果我们有 cat
|
||
if (flags & FLAG_C) { // 0101 & 0100 => 0100 => true
|
||
// do stuff
|
||
}
|
||
</code></pre>
|
||
<p>一个有多个位被置位的掩码表达任一/或者的含义。例如，以下两个表达是等价的：</p>
|
||
<pre><code class="language-javascript">// 如果我们有 bat 或者 cat 至少一个
|
||
// (0101 & 0010) || (0101 & 0100) => 0000 || 0100 => true
|
||
if ((flags & FLAG_B) || (flags & FLAG_C)) {
|
||
// do stuff
|
||
}
|
||
</code></pre>
|
||
<pre><code class="language-javascript">// 如果我们有 bat 或者 cat 至少一个
|
||
var mask = FLAG_B | FLAG_C; // 0010 | 0100 => 0110
|
||
if (flags & mask) { // 0101 & 0110 => 0100 => true
|
||
// do stuff
|
||
}
|
||
</code></pre>
|
||
<p>可以通过与掩码做或运算设置标志位，掩码中为 1 的位可以设置对应的位。例如掩码 1100 可用来设置位 C 和 D：</p>
|
||
<pre><code class="language-javascript">// 我们有 cat 和 duck
|
||
var mask = FLAG_C | FLAG_D; // 0100 | 1000 => 1100
|
||
flags |= mask; // 0101 | 1100 => 1101
|
||
</code></pre>
|
||
<p>可以通过与掩码做与运算清除标志位，掩码中为 0 的位可以设置对应的位。掩码可以通过对原语掩码做非运算得到。例如，掩码 1010 可以用来清除标志位 A 和 C ：</p>
|
||
<pre><code class="language-javascript">// 我们没有 ant 也没有 cat
|
||
var mask = ~(FLAG_A | FLAG_C); // ~0101 => 1010
|
||
flags &= mask; // 1101 & 1010 => 1000
|
||
</code></pre>
|
||
<p>如上的掩码同样可以通过 <code>~FLAG_A & ~FLAG_C</code> 得到（德摩根定律）：</p>
|
||
<pre><code class="language-javascript">// 我们没有 ant 也没有 cat
|
||
var mask = ~FLAG_A & ~FLAG_C;
|
||
flags &= mask; // 1101 & 1010 => 1000
|
||
</code></pre>
|
||
<p>标志位可以使用异或运算切换。所有值为 1 的为可以切换对应的位。例如，掩码 0110 可以用来切换标志位 B 和 C：</p>
|
||
<pre><code class="language-javascript">// 如果我们以前没有 bat ，那么我们现在有 bat
|
||
// 但是如果我们已经有了一个，那么现在没有了
|
||
// 对 cat 也是相同的情况
|
||
var mask = FLAG_B | FLAG_C;
|
||
flags = flags ^ mask; // 1100 ^ 0110 => 1010
|
||
</code></pre>
|
||
<p>最后，所有标志位可以通过非运算翻转:</p>
|
||
<pre><code class="language-javascript">// entering parallel universe...
|
||
flags = ~flags; // ~1010 => 0101
|
||
</code></pre>
|
||
<h3 id="转换片段">转换片段</h3>
|
||
<p>将一个二进制数的 <code><a href="Reference/Global_Objects/String" title="/en-US/docs/JavaScript/Reference/Global_Objects/String">String</a></code> 转换为十进制的 <code><a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Number" title="/en-US/docs/JavaScript/Reference/Global_Objects/Number">Number</a></code>:</p>
|
||
<pre><code class="language-javascript">var sBinString = "1011";
|
||
var nMyNumber = parseInt(sBinString, 2);
|
||
alert(nMyNumber); // 打印 11
|
||
</code></pre>
|
||
<p>将一个十进制的 <code><a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Number" title="/en-US/docs/JavaScript/Reference/Global_Objects/Number">Number</a></code> 转换为二进制数的 <code><a href="Reference/Global_Objects/String" title="/en-US/docs/JavaScript/Reference/Global_Objects/String">String</a></code>:</p>
|
||
<pre><code class="language-javascript">var nMyNumber = 11;
|
||
var sBinString = nMyNumber.toString(2);
|
||
alert(sBinString); // 打印 1011
|
||
</code></pre>
|
||
<h3 id="自动化掩码创建">自动化掩码创建</h3>
|
||
<p>如果你需要从一系列的 <code><a href="Reference/Global_Objects/Boolean" title="/en-US/docs/JavaScript/Reference/Global_Objects/Boolean">Boolean</a></code> 值创建一个掩码，你可以：</p>
|
||
<pre><code class="language-javascript">function createMask () {
|
||
var nMask = 0, nFlag = 0, nLen = arguments.length > 32 ? 32 : arguments.length;
|
||
for (nFlag; nFlag < nLen; nMask |= arguments[nFlag] << nFlag++);
|
||
return nMask;
|
||
}
|
||
var mask1 = createMask(true, true, false, true); // 11, i.e.: 1011
|
||
var mask2 = createMask(false, false, true); // 4, i.e.: 0100
|
||
var mask3 = createMask(true); // 1, i.e.: 0001
|
||
// etc.
|
||
|
||
alert(mask1); // 打印 11
|
||
</code></pre>
|
||
<h3 id="逆算法：从掩码得到布尔数组">逆算法：从掩码得到布尔数组</h3>
|
||
<p>如果你希望从掩码得到得到 <code><a href="Reference/Global_Objects/Boolean" title="/en-US/docs/JavaScript/Reference/Global_Objects/Boolean">Boolean</a></code> <code><a href="/zh-CN/docs/Mozilla/Tech/XPCOM/Array" title="/en-US/docs/JavaScript/Reference/Global_Objects/Array">Array</a></code> ：</p>
|
||
<pre><code class="language-javascript">function arrayFromMask (nMask) {
|
||
// nMask 必须介于 -2147483648 和 2147483647 之间
|
||
if (nMask > 0x7fffffff || nMask < -0x80000000) {
|
||
throw new TypeError("arrayFromMask - out of range");
|
||
}
|
||
for (var nShifted = nMask, aFromMask = []; nShifted;
|
||
aFromMask.push(Boolean(nShifted & 1)), nShifted >>>= 1);
|
||
return aFromMask;
|
||
}
|
||
|
||
var array1 = arrayFromMask(11);
|
||
var array2 = arrayFromMask(4);
|
||
var array3 = arrayFromMask(1);
|
||
|
||
alert("[" + array1.join(", ") + "]");
|
||
// 打印 "[true, true, false, true]", i.e.: 11, i.e.: 1011
|
||
</code></pre>
|
||
<p>你可以同时测试以上两个算法……</p>
|
||
<pre><code class="language-javascript">var nTest = 19; // our custom mask
|
||
var nResult = createMask.apply(this, arrayFromMask(nTest));
|
||
|
||
alert(nResult); // 19
|
||
</code></pre>
|
||
<p>仅仅由于教学目的 （因为有 <code><a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Number" title="/en-US/docs/JavaScript/Reference/Global_Objects/Number/toString">Number.toString(2)</a></code> 方法），我们展示如何修改 arrayFromMask 算法通过 Number 返回二进制的 String，而非 Boolean Array：</p>
|
||
<pre><code class="language-javascript">function createBinaryString (nMask) {
|
||
// nMask must be between -2147483648 and 2147483647
|
||
for (var nFlag = 0, nShifted = nMask, sMask = ""; nFlag < 32;
|
||
nFlag++, sMask += String(nShifted >>> 31), nShifted <<= 1);
|
||
return sMask;
|
||
}
|
||
|
||
var string1 = createBinaryString(11);
|
||
var string2 = createBinaryString(4);
|
||
var string3 = createBinaryString(1);
|
||
|
||
alert(string1);
|
||
// 打印 00000000000000000000000000001011, i.e. 11
|
||
</code></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>ECMAScript 1st Edition.</td>
|
||
<td>Standard</td>
|
||
<td>Initial definition.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-11.4.8" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">Bitwise NOT operator</small></a><br/>
|
||
<a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-11.7" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">Bitwise shift operators</small></a><br/>
|
||
<a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-11.10" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">Binary bitwise operators</small></a></td>
|
||
<td><span class="spec-Standard">Standard</span></td>
|
||
<td> </td>
|
||
</tr>
|
||
<tr>
|
||
<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-bitwise-not-operator" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Bitwise NOT operator</small></a><br/>
|
||
<a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-bitwise-shift-operators" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Bitwise shift operators</small></a><br/>
|
||
<a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-binary-bitwise-operators" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Binary bitwise operators</small></a></td>
|
||
<td><span class="spec-Standard">Standard</span></td>
|
||
<td> </td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
<h2 id="浏览器兼容性">浏览器兼容性</h2>
|
||
<p></p><div class="blockIndicator warning"><strong><a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">We're converting our compatibility data into a machine-readable JSON format</a></strong>.
|
||
This compatibility table still uses the old format,
|
||
because we haven't yet converted the data it contains.
|
||
<strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
|
||
<div class="htab">
|
||
<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
|
||
<ul>
|
||
<li class="selected"><a>Desktop</a></li>
|
||
<li><a>Mobile</a></li>
|
||
</ul>
|
||
</div><p></p>
|
||
<div id="compat-desktop">
|
||
<table class="compat-table">
|
||
<tbody>
|
||
<tr>
|
||
<th>Feature</th>
|
||
<th>Chrome</th>
|
||
<th>Firefox (Gecko)</th>
|
||
<th>Internet Explorer</th>
|
||
<th>Opera</th>
|
||
<th>Safari</th>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_NOT">Bitwise NOT (<code>~</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_AND">Bitwise AND (<code>&</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_OR">Bitwise OR (<code>|</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_XOR">Bitwise XOR (<code>^</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Left_shift">Left shift (<code><<</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Right_shift">Right shift (<code>>></code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Unsigned_right_shift">Unsigned right shift (<code>>>></code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
<div id="compat-mobile">
|
||
<table class="compat-table">
|
||
<tbody>
|
||
<tr>
|
||
<th>Feature</th>
|
||
<th>Android</th>
|
||
<th>Chrome for Android</th>
|
||
<th>Firefox Mobile (Gecko)</th>
|
||
<th>IE Mobile</th>
|
||
<th>Opera Mobile</th>
|
||
<th>Safari Mobile</th>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_NOT">Bitwise NOT (<code>~</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_AND">Bitwise AND (<code>&</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_OR">Bitwise OR (<code>|</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Bitwise_XOR">Bitwise XOR (<code>^</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Left_shift">Left shift (<code><<</code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Right_shift">Right shift (<code>>></code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
<tr>
|
||
<td><a href="#Unsigned_right_shift">Unsigned right shift (<code>>>></code>)</a></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
<h2 id="See_also" name="See_also">相关链接</h2>
|
||
<ul>
|
||
<li><a href="/en-US/docs/Web/JavaScript/Reference/Operators/Logical_Operators">Logical operators</a></li>
|
||
<li>
|
||
<p><strong>js ^</strong> & <strong>Bitwise Operators</strong></p>
|
||
</li>
|
||
</ul>
|
||
</article> |