## .ajaxSend( handler )Returns: jQuery

Description: Attach a function to be executed before an Ajax request is sent. This is an Ajax Event.

- #### version added: 1.0.ajaxSend( handler )

  - handler
    Type: Function( Event event, jqXHR jqXHR, PlainObject ajaxOptions )
    The function to be invoked.

Whenever an Ajax request is about to be sent, jQuery triggers the `ajaxSend` event. Any and all handlers that have been registered with the `.ajaxSend()` method are executed at this time.

To observe this method in action, set up a basic Ajax load request:

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    <div class="trigger">Trigger</div><div class="result"></div><div class="log"></div>

Attach the event handler to the document:

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    $( document ).ajaxSend(function() {  $( ".log" ).text( "Triggered ajaxSend handler." );});

Now, make an Ajax request using any jQuery method:

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    $( ".trigger" ).click(function() {  $( ".result" ).load( "ajax/test.html" );});

When the user clicks the element with class `trigger` and the Ajax request is about to begin, the log message is displayed.

All `ajaxSend` handlers are invoked, regardless of what Ajax request is to be sent. If you must differentiate between the requests, use the parameters passed to the handler. Each time an `ajaxSend` handler is executed, it is passed the event object, the `jqXHR` object (in version 1.4, `XMLHttpRequest`object), and the settings object that was used in the creation of the Ajax request. For example, you can restrict the callback to only handling events dealing with a particular URL:

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    $( document ).ajaxSend(function( event, jqxhr, settings ) {  if ( settings.url == "ajax/test.html" ) {    $( ".log" ).text( "Triggered ajaxSend handler." );  }});

### Additional Notes:

- As of jQuery 1.9, all the handlers for the jQuery global Ajax events, including those added with the `.ajaxSend()` method, must be attached to `document`.
- If `$.ajax()` or `$.ajaxSetup()` is called with the `global` option set to `false`, the `.ajaxSend()` method will not fire.

## Example:

Show a message before an Ajax request is sent.

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    $( document ).ajaxSend(function( event, request, settings ) {  $( "#msg" ).append( "<li>Starting request at " + settings.url + "</li>" );});