uTools-Manuals/docs/javascript/Reference/Global_Objects/Array/every.html

<article id="wikiArticle">
<div></div>
<h2 id="Summary" name="Summary">概述</h2>
<p><code><strong>every()</strong></code> 方法测试数组的所有元素是否都通过了指定函数的测试。</p>
<p><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/array-every.html" width="100%"></iframe></p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre><code class="language-javascript"><code><em>arr</em>.every(<em>callback</em>[, <em>thisArg</em>])</code></code></pre>
<h3 id="Parameters" name="Parameters">参数</h3>
<dl>
<dt><code>callback</code></dt>
<dd>用来测试每个元素的函数。</dd>
<dt><code>thisArg</code></dt>
<dd>执行 <code>callback</code> 时使用的 <code>this</code> 值。</dd>
</dl>
<h2 id="Description" name="Description">描述</h2>
<p><code>every</code> 方法为数组中的每个元素执行一次 <code>callback</code> 函数，直到它找到一个使 <code>callback</code> 返回 <em>false</em>（表示可转换为布尔值 false 的值）的元素。如果发现了一个这样的元素，<code>every</code> 方法将会立即返回 <code>false</code>。否则，<code>callback</code> 为每一个元素返回 <code>true</code>，<code>every</code> 就会返回 <code>true</code>。<code>callback</code> 只会为那些已经被赋值的索引调用。不会为那些被删除或从来没被赋值的索引调用。</p>
<p><code>callback</code> 被调用时传入三个参数：元素值，元素的索引，原数组。</p>
<p>如果为 <code>every</code> 提供一个 <code>thisArg</code> 参数，则该参数为调用 <code>callback</code> 时的 <code>this</code> 值。如果省略该参数，则 <code>callback</code> 被调用时的 <code>this</code> 值，在非严格模式下为全局对象，在严格模式下传入 <code>undefined</code>。</p>
<p><code>every</code> 不会改变原数组。</p>
<p><code>every</code> 遍历的元素范围在第一次调用 <code>callback</code> 之前就已确定了。在调用 <code>every</code> 之后添加到数组中的元素不会被 <code>callback</code> 访问到。如果数组中存在的元素被更改，则他们传入 <code>callback</code> 的值是 <code>every</code> 访问到他们那一刻的值。那些被删除的元素或从来未被赋值的元素将不会被访问到。</p>
<p><code>every</code> 和数学中的"所有"类似，当所有的元素都符合条件才返回true。另外，空数组也是返回true。(空数组中所有元素都符合给定的条件，注：因为空数组没有元素)。</p>
<h2 id="Examples" name="Examples">实例</h2>
<h3 id="Example:_Testing_size_of_all_array_elements" name="Example:_Testing_size_of_all_array_elements">例子：检测所有数组元素的大小</h3>
<p>下例检测数组中的所有元素是否都大于 10。</p>
<pre><code  class="language-javascript">function isBigEnough(element, index, array) {
  return (element &gt;= 10);
}
var passed = [12, 5, 8, 130, 44].every(isBigEnough);
// passed is false
passed = [12, 54, 18, 130, 44].every(isBigEnough);
// passed is true
</code></pre>
<h2 id="Compatibility" name="Compatibility">兼容旧环境（Polyfill）</h2>
<p>在第 5 版时，<code>every</code> 被添加进 ECMA-262 标准；因此在某些实现环境中不被支持。你可以把下面的代码放到脚本的开头来解决此问题，该代码允许在那些没有原生支持 <code>every</code> 的实现环境中使用它。该算法是 ECMA-262 第5版中指定的算法，假定 <code>Object</code> 和 <code>TypeError</code> 拥有它们的初始值，且 <code>fun.call</code> 等价于 <a href="Reference/Global_Objects/Function/call" title="call() 方法调用一个函数, 其具有一个指定的this值和分别地提供的参数(参数的列表)。"><code>Function.prototype.call</code></a>。</p>
<pre><code  class="language-javascript">if (!Array.prototype.every)
{
  Array.prototype.every = function(fun /*, thisArg */)
  {
    'use strict';

    if (this === void 0 || this === null)
      throw new TypeError();

    var t = Object(this);
    var len = t.length &gt;&gt;&gt; 0;
    if (typeof fun !== 'function')
        throw new TypeError();

    var thisArg = arguments.length &gt;= 2 ? arguments[1] : void 0;
    for (var i = 0; i &lt; len; i++)
    {
      if (i in t &amp;&amp; !fun.call(<span style="line-height: normal;">thisArg</span><span style="line-height: normal;">, t[i], i, t))</span>
        return false;
    }

    return true;
  };
}
</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><a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.16" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">Array.prototype.every</small></a></td>
<td><span class="spec-Standard">Standard</span></td>
<td>Initial definition.<br/>
    Implemented in JavaScript 1.6</td>
</tr>
<tr>
<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.every" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Array.prototype.every</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>
<div>
<div class="hidden">The compatibility table in 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>
<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>every</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">
<span>Full support</span>
</abbr>
              Yes</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">
<span>Full support</span>
</abbr>
              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">
<span>Full support</span>
</abbr>
              1.5</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">
<span>Full support</span>
</abbr>
              9</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">
<span>Full support</span>
</abbr>
              Yes</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">
<span>Full support</span>
</abbr>
              Yes</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">
<span>Full support</span>
</abbr>
              Yes</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">
<span>Full support</span>
</abbr>
              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">
<span>Full support</span>
</abbr>
              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">
<span>Full support</span>
</abbr>
              4</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">
<span>Full support</span>
</abbr>
              Yes</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">
<span>Full support</span>
</abbr>
              Yes</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">
<span>Full support</span>
</abbr>
              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">
<span>Full support</span>
</abbr>
              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">
<abbr class="bc-level bc-level-yes only-icon" title="Full support">
<span>Full support</span>
                  
                </abbr></span></dt><dd>Full support</dd></dl></section></div><p></p>
</div>
<h2 id="See_also" name="See_also">相关链接</h2>
<ul>
<li><a href="Reference/Global_Objects/Array/forEach" title="forEach() 方法对数组的每个元素执行一次提供的函数。"><code>Array.prototype.forEach()</code></a></li>
<li><a href="Reference/Global_Objects/Array/some" title="some() 方法测试是否至少有一个元素通过由提供的函数实现的测试。"><code>Array.prototype.some()</code></a></li>
</ul>
</article>