uTools-Manuals/docs/jQuery/ajaxSend.html

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<h1 class="entry-title">.ajaxSend()</h1>
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						所属分类：<span class="category"><a href="/category/ajax/">Ajax</a> &gt; <a href="/category/ajax/global-ajax-event-handlers/">全局 Ajax 事件处理器</a></span>
<span class="pull-right">英文文档：<a href="https://api.jquery123.com/ajaxSend/" target="_blank">.ajaxSend()</a></span>
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<span class="name">.ajaxSend( handler(event, jqXHR, ajaxOptions) )</span><span class="returns">返回: <a href="/Types/#jQuery">jQuery</a></span>
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<p class="desc"><strong>描述: </strong>在Ajax请求发送之前绑定一个要执行的函数，这是一个 <a href="/Ajax_Events">Ajax Event</a>.</p>
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<span class="version-details">添加的版本: <a href="/category/version/1.0/">1.0</a></span>.ajaxSend( handler(event, jqXHR, ajaxOptions) )</h4>
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<div><strong>handler(event, jqXHR, ajaxOptions)</strong></div>
<div>类型: <a href="/Types/#Function">Function</a>()</div>
<div>被调用的函数。</div>
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<p>每当一个Ajax请求即将发送，jQuery就会触发<code>ajaxSend</code>事件，在这个时间点所有处理函数都会使用<code>.ajaxSend()</code>方法注册并执行。</p>
<p>观察这种方法，建立一个基本的Ajax加载请求：</p>
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<pre><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span> <span class="attribute">class</span>=<span class="value">"trigger"</span>&gt;</span>Trigger<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">class</span>=<span class="value">"result"</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">class</span>=<span class="value">"log"</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div></pre>
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<p>在document上绑定事件处理器：</p>
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<pre><div class="container"><div class="line"><code>$(document).ajaxSend(<span class="keyword">function</span>() {</code></div></div><div class="container"><div class="line"><code>  $( <span class="string">".log"</span> ).text( <span class="string">"Triggered ajaxSend handler."</span> );</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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<p>现在，我们可以使用任何的jQuery方法构建一个Ajax请求：</p>
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<pre><div class="container"><div class="line"><code>$( <span class="string">".trigger"</span> ).click(<span class="keyword">function</span>() {</code></div></div><div class="container"><div class="line"><code>  $( <span class="string">".result"</span> ).load( <span class="string">"ajax/test.html"</span> );</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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<p>当我们点击class为 <code>trigger</code> 的元素并且Ajax请求即将开始，这个信息就会显示。
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<p><strong>但是从 jQuery 1.8 开始, <code>.ajaxSend()</code> 方法只能绑定到 <code>document</code>元素.</strong></p>
<p><strong>注，这段在官网的原文中已经被删除:</strong> 因为<code>.ajaxComplete()</code> 是作为一个jQuery对象实例方法去执行的，回调函数中，我们可以用<code>this</code>关键字作为指定的元素。</p>
<p>无论哪一个Ajax请求被发送，所有<code>ajaxSend</code>处理器都将被执行。如果我们必须区分不同的请求,我们可以使参数传递给这个处理器。 每次<code>ajaxSend</code> 处理器执行，它传递事件对象，<code>jqXHR</code>对象（在 jQuery 1.4中是<code><abbr title="XMLHttpRequest">XMLHttpRequest</abbr></code>对象），和用来创建请求的设置（<a href="/jQuery.ajax">settings object</a>）对象。如果请求失败，因为JavaScript抛出一个异常，并且作为第四个参数的异常对象被传递给处理程序。举个例子,我们能限制我们的回调到只处理事件处理某一特定的URL:</p>
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<pre><div class="container"><div class="line"><code>$(document).ajaxSend(<span class="keyword">function</span>(event, jqxhr, settings) {</code></div></div><div class="container"><div class="line"><code>  <span class="keyword">if</span> ( settings.url == <span class="string">"ajax/test.html"</span> ) {</code></div></div><div class="container"><div class="line"><code>    $( <span class="string">".log"</span> ).text( <span class="string">"Triggered ajaxSend handler."</span> );</code></div></div><div class="container"><div class="line"><code>  }</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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<h3>其他注意事项：</h3>
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			                如果<code>global</code>选项设置为<code>false</code>，调用<code><a href="/jQuery.Ajax">$.ajax()</a></code> 或 <code><a href="/jQuery.ajaxSend">.ajaxSend()</a></code>方法将不会被触发。</li>
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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><span class="desc">当Ajax请求即将发送前显示一个信息。</span></h4>
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<pre><div class="container"><div class="line"><code>$(document).ajaxSend(<span class="keyword">function</span>(event, request, settings) {</code></div></div><div class="container"><div class="line"><code>    $( <span class="string">"#msg"</span> ).append( <span class="string">"&lt;li&gt;Starting request at "</span> + settings.url + <span class="string">"&lt;/li&gt;"</span> );</code></div></div><div class="container"><div class="line"><code>});</code></div></div></pre>
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