ajaxStart.xml

<?xml version="1.0"?>
<entry type="method" name="on" return="jQuery">
  <title>ajaxStart event</title>
  <desc>Register a handler to be called when the first Ajax request begins. This is an <a href="/Ajax_Events/">Ajax Event</a>.</desc>
  <signature>
    <added>1.7</added>
    <argument name="&quot;ajaxStart&quot;" type="string">
      <desc>The string <code>"ajaxStart"</code>.</desc>
    </argument>
    <argument name="handler" type="Function">
      <desc>The function to be invoked.</desc>
    </argument>
  </signature>
  <longdesc>
    <div class="warning">
      <p>This page describes the <code>ajaxStart</code> event. For the deprecated <code>.ajaxStart()</code> method, see <a href="/ajaxStart-shorthand/"><code>.ajaxStart()</code></a>.</p>
    </div>
    <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 <code>.on( "ajaxStart", ... )</code> are executed at this time.</p>
    <p>To observe this method in action, set up a basic Ajax load request:</p>
    <pre><code>
&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;
    </code></pre>
    <p>Attach the event handler to any element:</p>
    <pre><code>
$( document ).on( "ajaxStart", function() {
  $( ".log" ).text( "Triggered ajaxStart handler." );
} );
    </code></pre>
    <p>Now, make an Ajax request using any jQuery method:</p>
    <pre><code>
$( ".trigger" ).on( "click", function() {
  $( ".result" ).load( "ajax/test.html" );
} );
    </code></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>
  </longdesc>
  <note id="global-ajax-event" type="additional" data-title="ajaxStart"/>
  <note id="ajax-global-false" type="additional" data-title="ajaxStart"/>
  <example>
    <desc>Show a loading message whenever an Ajax request starts (and none is already active).</desc>
    <code><![CDATA[
$( document ).on( "ajaxStart", function() {
  $( "#loading" ).show();
} );
]]></code>
  </example>
  <category slug="ajax/global-ajax-event-handlers"/>
  <category slug="version/1.0"/>
  <category slug="version/1.7"/>
</entry>