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113 lines
6.9 KiB
HTML
113 lines
6.9 KiB
HTML
<article id="wikiArticle">
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<p></p><p></p>
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<h2 id="Summary" name="Summary" style="margin-bottom: 20px; line-height: 30px;">概述</h2>
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<p><strong>length</strong> 属性表示一个字符串的长度。</p>
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<h2 id="Description" name="Description" style="margin-bottom: 20px; line-height: 30px;">描述</h2>
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<p>该属性返回字符串中字符编码单元的数量。JavaScript 使用 <a class="external" href="https://zh.wikipedia.org/wiki/UTF-16" rel="noopener" title="UTF-16">UTF-16</a> 编码，该编码使用一个 16 比特的编码单元来表示大部分常见的字符，使用两个代码单元表示不常用的字符。因此 length 返回值可能与字符串中实际的字符数量不相同。</p>
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<p>空字符串的 <code>length</code> 为 0。</p>
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<p>静态属性 <strong>String.length</strong> 返回 1。</p>
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<h2 id="Examples" name="Examples" style="margin-bottom: 20px; line-height: 30px;">示例</h2>
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<pre><code class="language-javascript">var x = "Mozilla";
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var empty = "";
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console.log("Mozilla is " + x.length + " code units long");
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/* "Mozilla is 7 code units long" */
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console.log("The empty string is has a length of " + empty.length);
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/* "The empty string is has a length of 0" */</code></pre>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 0px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 19px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 38px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 57px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 76px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 95px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 114px; background: 0px 0px;"> </div>
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<div class="line-number" style="margin-top: 1em; position: absolute; left: 0px; right: 0px; line-height: inherit; top: 133px; background: 0px 0px;"> </div>
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<h2 id="规范" style="margin-bottom: 20px; line-height: 30px;">规范</h2>
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<table class="standard-table">
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<tbody>
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<tr>
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<th scope="col">Specification</th>
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<th scope="col">Status</th>
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<th scope="col">Comment</th>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%201st%20edition,%20June%201997.pdf" hreflang="en" lang="en" rel="noopener" title="ECMAScript 1st Edition (ECMA-262)">ECMAScript 1st Edition (ECMA-262)</a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition. Implemented in JavaScript 1.0.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-15.5.5.1" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">String.prototype.length</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td> </td>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-string-instances-length" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">String.prototype.length</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td> </td>
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</tr>
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</tbody>
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</table>
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<h2 id="浏览器兼容性" style="margin-bottom: 20px; line-height: 30px;">浏览器兼容性</h2>
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<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>.
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This compatibility table still uses the old format,
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because we haven't yet converted the data it contains.
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<strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
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<div class="htab">
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<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
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<ul>
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<li class="selected"><a>Desktop</a></li>
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<li><a>Mobile</a></li>
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</ul>
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</div><p></p>
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<div id="compat-desktop">
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<table class="compat-table">
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<tbody>
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<tr>
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<th style="line-height: 16px;">Feature</th>
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<th style="line-height: 16px;">Chrome</th>
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<th style="line-height: 16px;">Firefox (Gecko)</th>
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<th style="line-height: 16px;">Internet Explorer</th>
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<th style="line-height: 16px;">Opera</th>
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<th style="line-height: 16px;">Safari</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<div id="compat-mobile">
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<table class="compat-table">
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<tbody>
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<tr>
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<th style="line-height: 16px;">Feature</th>
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<th style="line-height: 16px;">Android</th>
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<th style="line-height: 16px;">Chrome for Android</th>
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<th style="line-height: 16px;">Firefox Mobile (Gecko)</th>
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<th style="line-height: 16px;">IE Mobile</th>
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<th style="line-height: 16px;">Opera Mobile</th>
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<th style="line-height: 16px;">Safari Mobile</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<h2 id="See_also" name="See_also" style="margin-bottom: 20px; line-height: 30px;">相关链接</h2>
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<ul>
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<li><a class="external external-icon" href="http://developer.teradata.com/blog/jasonstrimpel/2011/11/javascript-string-length-and-internationalizing-web-applications" rel="noopener" style="white-space: pre-line;">JavaScript String.length and Internationalizing Web Applications</a></li>
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</ul>
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</article> |