uTools-Manuals/docs/jQuery/jQuery.each.html

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<h1 class="entry-title">jQuery.each()</h1>
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						所属分类：<span class="category"><a href="/category/utilities/">工具类</a></span>
<span class="pull-right">英文文档：<a href="https://api.jquery123.com/jQuery.each/" target="_blank">jQuery.each()</a></span>
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<article class="entry method" id="jQuery-each1"><h2 class="section-title">
<span class="name">jQuery.each( collection, callback(indexInArray, valueOfElement) )</span><span class="returns">返回: <a href="/Types/#Object">Object</a></span>
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<p class="desc"><strong>描述: </strong>
			一个通用的迭代函数，它可以用来无缝迭代对象和数组。数组和类似数组的对象通过一个长度属性（如一个函数的参数对象）来迭代数字索引，从0到length - 1。其他对象通过其属性名进行迭代。</p>
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<span class="version-details">添加的版本: <a href="/category/version/1.0/">1.0</a></span>jQuery.each( collection, callback(indexInArray, valueOfElement) )</h4>
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<div><strong>collection</strong></div>
<div>类型: <a href="/Types/#Object">Object</a>
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<div>遍历的对象或数组。</div>
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<div><strong>callback(indexInArray, valueOfElement)</strong></div>
<div>类型: <a href="/Types/#Function">Function</a>()</div>
<div>该函数会在每次迭代时被调用。</div>
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<p><code>$.each()</code>函数和<a href="/each"> $(selector).each()</a>是不一样的，那个是专门用来遍历一个jQuery对象。<code>$.each()</code>函数可用于迭代任何集合，无论是“名/值”对象（JavaScript对象）或数组。在迭代数组的情况下，回调函数每次传递一个数组索引和相应的数组值作为参数。（该值也可以通过访问<code>this</code>关键字得到，但是JavaScript将始终将<code>this</code>值作为一个<code>Object</code> ，即使它是一个简单的字符串或数字值。）该方法返回其第一个参数，这是迭代的对象。</p>
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<pre><div class="container"><div class="line"><code>$.each([<span class="number">52</span>, <span class="number">97</span>], <span class="keyword">function</span>(index, value) {</code></div></div><div class="container"><div class="line"><code>  alert(index + <span class="string">': '</span> + value);</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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<p>这将产生两个信息：</p>
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<span class="output">0: 52</span>
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<span class="output">1: 97</span>
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<p>如果对象是作为集合使用，回调函数每次传递一个键值对的：</p>
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<pre><div class="container"><div class="line"><code><span class="keyword">var</span> obj = {</code></div></div><div class="container"><div class="line"><code>  <span class="string">"flammable"</span>: <span class="string">"inflammable"</span>,</code></div></div><div class="container"><div class="line"><code>  <span class="string">"duh"</span>: <span class="string">"no duh"</span></code></div></div><div class="container"><div class="line"><code>};</code></div></div><div class="container"><div class="line"><code>$.each( obj, <span class="keyword">function</span>( key, value ) {</code></div></div><div class="container"><div class="line"><code>  alert( key + <span class="string">": "</span> + value );</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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<p>再次，这将产生两个信息：</p>
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<span class="output">flammable: inflammable</span>
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<span class="output">duh: no duh</span>
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<p>我们可以在<code>$.each()</code>返回<code>false</code>来终止迭代。返回<em>非false</em>相当于一个循环中的<code>continue</code>语句，这意味着，它会立即跳出当前的迭代，转到下一个迭代。</p>
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<section class="entry-examples" id="entry-examples"><header><h2 class="underline">例子:</h2></header><div class="entry-example" id="example-0">
<h4>Example: <span class="desc">对数组进行迭代，迭代过程中同时显示关键字及数值</span>
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<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!doctype html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span> <span class="attribute">lang</span>=<span class="value">"en"</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">meta</span> <span class="attribute">charset</span>=<span class="value">"utf-8"</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">title</span>&gt;</span>jQuery.each demo<span class="tag">&lt;/<span class="title">title</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"></span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">div</span> <span class="rules">{</span></code></div></div><div class="container"><div class="line"><code>    <span class="rule"><span class="attribute">color</span>:<span class="value"> blue;</span></span></code></div></div><div class="container"><div class="line"><code>  <span class="rule">}</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">div</span><span class="id">#five</span> <span class="rules">{</span></code></div></div><div class="container"><div class="line"><code>    <span class="rule"><span class="attribute">color</span>:<span class="value"> red;</span></span></code></div></div><div class="container"><div class="line"><code>  <span class="rule">}</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-1.9.1.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span> <span class="attribute">id</span>=<span class="value">"one"</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span> <span class="attribute">id</span>=<span class="value">"two"</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span> <span class="attribute">id</span>=<span class="value">"three"</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span> <span class="attribute">id</span>=<span class="value">"four"</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span> <span class="attribute">id</span>=<span class="value">"five"</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"></span></code></div></div><div class="container"><div class="line"><code><span class="keyword">var</span> arr = [ <span class="string">"one"</span>, <span class="string">"two"</span>, <span class="string">"three"</span>, <span class="string">"four"</span>, <span class="string">"five"</span> ];</code></div></div><div class="container"><div class="line"><code><span class="keyword">var</span> obj = { one: <span class="number">1</span>, two: <span class="number">2</span>, three: <span class="number">3</span>, four: <span class="number">4</span>, five: <span class="number">5</span> };</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code>jQuery.each( arr, <span class="keyword">function</span>( i, val ) {</code></div></div><div class="container"><div class="line"><code>  $( <span class="string">"#"</span> + val ).text( <span class="string">"Mine is "</span> + val + <span class="string">"."</span> );</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code>  <span class="comment">// Will stop running after "three"</span></code></div></div><div class="container"><div class="line"><code>  <span class="keyword">return</span> ( val !== <span class="string">"three"</span> );</code></div></div><div class="container"><div class="line"><code>});</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code>jQuery.each( obj, <span class="keyword">function</span>( i, val ) {</code></div></div><div class="container"><div class="line"><code>  $( <span class="string">"#"</span> + i ).append( document.createTextNode( <span class="string">" - "</span> + val ) );</code></div></div><div class="container"><div class="line"><code>});</code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
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<h4>Demo:</h4>
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<h4>Example: <span class="desc">迭代一个数组，并同时访问迭代的元素及它的索引值。</span>
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<pre><div class="container"><div class="line"><code>$.each( [<span class="string">'a'</span>,<span class="string">'b'</span>,<span class="string">'c'</span>], <span class="keyword">function</span>(i, l){</code></div></div><div class="container"><div class="line"><code>   alert( <span class="string">"Index #"</span> + i + <span class="string">": "</span> + l );</code></div></div><div class="container"><div class="line"><code> });</code></div></div></pre>
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<div class="entry-example" id="example-2">
<h4>Example: <span class="desc">在一个元素的属性上进行迭代，并同时访问它的键及值。</span>
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<pre><div class="container"><div class="line"><code>$.each( { name: <span class="string">"John"</span>, lang: <span class="string">"JS"</span> }, <span class="keyword">function</span>(k, v){</code></div></div><div class="container"><div class="line"><code>   alert( <span class="string">"Key: "</span> + k + <span class="string">", Value: "</span> + v );</code></div></div><div class="container"><div class="line"><code> });</code></div></div></pre>
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