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115 lines
5.2 KiB
HTML
115 lines
5.2 KiB
HTML
<article id="wikiArticle">
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<div></div>
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<p><strong><code>Number.MIN_SAFE_INTEGER</code></strong> 代表在 JavaScript中最小的安全的integer型数字 (<code>-(2<sup>53</sup> - 1)</code>).</p>
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<div><table class="standard-table">
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<thead>
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<tr>
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<th class="header" colspan="2"><code>Number.MIN_SAFE_INTEGER</code> 属性的属性特性：</th>
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</tr>
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</thead>
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<tbody>
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<tr>
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<td>writable</td>
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<td>false</td>
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</tr>
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<tr>
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<td>enumerable</td>
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<td>false</td>
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</tr>
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<tr>
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<td>configurable</td>
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<td>false</td>
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</tr>
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</tbody>
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</table></div>
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<h2 id="描述">描述</h2>
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<p><code>MIN_SAFE_INTEGER</code> 的值是<code>-9007199254740991</code>. 形成这个数字的原因是 JavaScript 在 <a class="external" href="http://en.wikipedia.org/wiki/IEEE_floating_point" rel="noopener">IEEE 754</a>中使用<a class="external" href="http://en.wikipedia.org/wiki/Double_precision_floating-point_format" rel="noopener">double-precision floating-point format numbers</a> 作为规定。在这个规定中能安全的表示数字的范围在<code>-(2<sup>53</sup> - 1)</code> 到 <code>2<sup>53</sup> - 1之间</code>.</p>
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<p><code><font face="Open Sans, Arial, sans-serif">由于</font>MIN_SAFE_INTEGER</code> 是<a href="Reference/Global_Objects/Number" title="JavaScript 的 Number 对象是经过封装的能让你处理数字值的对象。Number 对象由 Number() 构造器创建。"><code>Number</code></a>的一个静态属性,你可以直接使用<code>Number.MIN_SAFE_INTEGER</code>, r而不是自己去创建一个<a href="Reference/Global_Objects/Number" title="JavaScript 的 Number 对象是经过封装的能让你处理数字值的对象。Number 对象由 Number() 构造器创建。"><code>Number</code></a>的属性。 </p>
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<h2 id="示例">示例</h2>
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<pre><code class="language-javascript">Number.MIN_SAFE_INTEGER // -9007199254740991
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-(Math.pow(2, 53) - 1) // -9007199254740991
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</code></pre>
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<h2 id="规范">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/ecma-262/6.0/#sec-number.min_safe_integer" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Number.MIN_SAFE_INTEGER</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-number.min_safe_integer" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Number.MIN_SAFE_INTEGER</small></a></td>
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<td><span class="spec-Draft">Draft</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="浏览器支持">浏览器支持</h2>
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<div><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></div>
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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>Feature</th>
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<th>Chrome</th>
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<th>Firefox (Gecko)</th>
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<th>Internet Explorer</th>
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<th>Opera</th>
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<th>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>34</td>
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<td><a href="/en-US/Firefox/Releases/31" title="Released on 2014-07-22.">31</a> (31)</td>
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<td><span style="color: #f00;">未实现</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: #f00;">未实现</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>Feature</th>
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<th>Android</th>
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<th>Chrome for Android</th>
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<th>Firefox Mobile (Gecko)</th>
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<th>IE Mobile</th>
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<th>Opera Mobile</th>
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<th>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>32.0 (32)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</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="参阅">参阅</h2>
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<ul>
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<li><a href="Reference/Global_Objects/Number/MAX_SAFE_INTEGER" title="Number.MAX_SAFE_INTEGER 常量表示在 JavaScript 中最大的安全整数（maxinum safe integer)（253 - 1）。"><code>Number.MAX_SAFE_INTEGER</code></a></li>
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<li><a href="Reference/Global_Objects/Number/isSafeInteger" title="Number.isSafeInteger() 方法用来判断传入的参数值是否是一个“安全整数”（safe integer）。一个安全整数是一个符合下面条件的整数："><code>Number.isSafeInteger()</code></a></li>
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</ul>
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</article> |