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112 lines
9.7 KiB
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<article id="wikiArticle">
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<div></div>
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<p><strong><code>getFloat64()</code></strong><code>方法</code><code>从</code><a href="https://developer.mozilla.orgReference/Global_Objects/DataView" title="DataView 视图提供了一种用于向 ArrayBuffer 读写数据的底层接口。"><code>DataView</code></a>起始位置以byte为计数的指定偏移量(byteOffset)处获取一个64-bit数(双精度浮点型).</p>
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<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/dataview-getfloat64.html" width="100%"></iframe></div>
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<p 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 class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
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<h2 id="语法">语法</h2>
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<pre><code class="language-javascript"><var>dataview</var>.getFloat64(byteOffset [, littleEndian])</code></pre>
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<h3 id="参数">参数</h3>
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<dl>
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<dt>byteOffset</dt>
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<dd>偏移量, 单位为字节, 从头开始计算.</dd>
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<dt>littleEndian</dt>
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<dd><span class="inlineIndicator optional optionalInline">可选</span> Indicates whether the 64-bit float is stored in <a class="glossaryLink" href="/en-US/docs/Glossary/Endianness" title='little- or big-endian: "Endian" and "endianness" (or "byte-order") describe how computers organize the bytes that make up numbers.'>little- or big-endian</a> format. If false or undefined, a big-endian value is read.</dd>
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</dl>
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<h3 id="返回">返回</h3>
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<dl>
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<dd>一个双精度浮点型64位数.</dd>
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</dl>
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<h3 id="抛出错误">抛出错误</h3>
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<dl>
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<dt><a href="Reference/Global_Objects/RangeError" title="RangeError对象标明一个错误，当一个值不在其所允许的范围或者集合中。"><code>RangeError</code></a></dt>
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<dd>如果byteOffset超出了视图能储存的值，就会抛出错误.</dd>
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</dl>
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<h2 id="描述">描述</h2>
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<dl>
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<dd>没有对齐约束; 多字节值可以从任何偏移量获取.</dd>
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</dl>
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<h2 id="例子">例子</h2>
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<pre><code class="language-js">var buffer = new ArrayBuffer(8);
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var dataview = new DataView(buffer);
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dataview.getFloat64(1); // 0
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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.khronos.org/registry/typedarray/specs/latest/" hreflang="en" lang="en" rel="noopener" title="Typed Array Specification">Typed Array Specification</a></td>
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<td><span class="spec-Obsolete">Obsolete</span></td>
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<td>Superseded by ECMAScript 6.</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-dataview.prototype.getfloat64" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">DataView.prototype.getFloat64</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition in ECMA standard.</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-dataview.prototype.getfloat64" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">DataView.prototype.getFloat64</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 class="hidden">The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out <a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</div>
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<p></p><div class="bc-data"><a class="bc-github-link external" href="https://github.com/mdn/browser-compat-data" rel="noopener">Update compatibility data on GitHub</a><table class="bc-table bc-table-js"><thead><tr class="bc-platforms"><td></td><th class="bc-platform-desktop" colspan="6"><span>Desktop</span></th><th class="bc-platform-mobile" colspan="7"><span>Mobile</span></th><th class="bc-platform-server" colspan="1"><span>Server</span></th></tr><tr class="bc-browsers"><td></td><th class="bc-browser-chrome"><span class="bc-head-txt-label bc-head-icon-chrome">Chrome</span></th><th class="bc-browser-edge"><span class="bc-head-txt-label bc-head-icon-edge">Edge</span></th><th class="bc-browser-firefox"><span class="bc-head-txt-label bc-head-icon-firefox">Firefox</span></th><th class="bc-browser-ie"><span class="bc-head-txt-label bc-head-icon-ie">Internet Explorer</span></th><th class="bc-browser-opera"><span class="bc-head-txt-label bc-head-icon-opera">Opera</span></th><th class="bc-browser-safari"><span class="bc-head-txt-label bc-head-icon-safari">Safari</span></th><th class="bc-browser-webview_android"><span class="bc-head-txt-label bc-head-icon-webview_android">Android webview</span></th><th class="bc-browser-chrome_android"><span class="bc-head-txt-label bc-head-icon-chrome_android">Chrome for Android</span></th><th class="bc-browser-edge_mobile"><span class="bc-head-txt-label bc-head-icon-edge_mobile">Edge Mobile</span></th><th class="bc-browser-firefox_android"><span class="bc-head-txt-label bc-head-icon-firefox_android">Firefox for Android</span></th><th class="bc-browser-opera_android"><span class="bc-head-txt-label bc-head-icon-opera_android">Opera for Android</span></th><th class="bc-browser-safari_ios"><span class="bc-head-txt-label bc-head-icon-safari_ios">Safari on iOS</span></th><th class="bc-browser-samsunginternet_android"><span class="bc-head-txt-label bc-head-icon-samsunginternet_android">Samsung Internet</span></th><th class="bc-browser-nodejs"><span class="bc-head-txt-label bc-head-icon-nodejs">Node.js</span></th></tr></thead><tbody><tr><th scope="row"><code>getFloat64</code></th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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9</td><td class="bc-supports-yes bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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12</td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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15</td><td class="bc-supports-yes bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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10</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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12.1</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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5.1</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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4</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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15</td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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12</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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4.2</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td></tr></tbody></table><section class="bc-legend" id="sect1"><h3 class="offscreen" id="Legend">Legend</h3><dl><dt><span class="bc-supports-yes bc-supports">
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<abbr class="bc-level bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr></span></dt><dd>Full support</dd></dl></section></div><p></p>
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<h2 id="另见">另见</h2>
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<ul>
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<li><a href="Reference/Global_Objects/DataView" title="DataView 视图是一个可以从 ArrayBuffer 对象中读写多种数值类型的底层接口，使用它时，不用考虑不同平台的字节序问题。"><code>DataView</code></a></li>
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<li><a href="Reference/Global_Objects/ArrayBuffer" title="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 https://github.com/mdn/interactive-examples and send us a pull request."><code>ArrayBuffer</code></a></li>
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</ul>
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</article> |