ajaxStart.xml

<entry type='method' name="ajaxStart" return="jQuery">
  <signature>
    <added>1.0</added>
    <argument name="handler()" type="Function">
      <desc>The function to be invoked.</desc>
    </argument>
  </signature>
  <desc>Register a handler to be called when the first Ajax request begins. This is an <a href='http://docs.jquery.com/Ajax_Events'>Ajax Event</a>.</desc>
  <longdesc><p>Whenever an Ajax request is about to be sent, jQuery checks whether there are any other outstanding Ajax requests. If none are in progress, jQuery triggers the <code>ajaxStart</code> event. Any and all handlers that have been registered with the <code>.ajaxStart()</code> method are executed at this time.</p>
    <p>To observe this method in action, we can set up a basic Ajax load request:</p>
    <pre>&lt;div class="trigger"&gt;Trigger&lt;/div&gt;
&lt;div class="result"&gt;&lt;/div&gt;
&lt;div class="log"&gt;&lt;/div&gt;</pre>
    <p>We can attach our event handler to any element:</p>
    <pre>$('.log').ajaxStart(function() {
  $(this).text('Triggered ajaxStart handler.');
});</pre>
    <p>Now, we can make an Ajax request using any jQuery method:</p>
    <pre>$('.trigger').click(function() {
  $('.result').load('ajax/test.html');
});</pre>
    <p>When the user clicks the element with class <code>trigger</code> and the Ajax request is sent, the log message is displayed.</p>

    <p><strong>Note:</strong> Because <code>.ajaxStart()</code> is implemented as a method of jQuery object instances, we can use the <code>this</code> keyword as we do here to refer to the selected elements within the callback function.</p>
  </longdesc>
  <example>
    <desc>Show a loading message whenever an Ajax request starts (and none is already active).</desc>
    <code><![CDATA[$("#loading").ajaxStart(function(){
   $(this).show();
 });]]></code>
  </example>
  <category slug="ajax/global-ajax-event-handlers"/>
  <category slug="version/1.0"/>
</entry>