.ajaxStart( handler() ) Returns: jQuery
Description: Register a handler to be called when the first Ajax request begins. This is an Ajax Event.
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 ajaxStart
event. Any and all handlers that have been registered with the .ajaxStart()
method are executed at this time.
To observe this method in action, set up a basic Ajax load request:
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Attach the event handler to any element:
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Now, make an Ajax request using any jQuery method:
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When the user clicks the element with class trigger
and the Ajax request is sent, the log message is displayed.
Note: Because .ajaxStart()
is implemented as a method of jQuery object instances, you can use the this
keyword to refer to the selected elements within the callback function. As of jQuery 1.8, however, the .ajaxStart()
method should only be attached to document
.
Additional Notes:
- If
$.ajax()
or$.ajaxSetup()
is called with theglobal
option set tofalse
, the.ajaxStart()
method will not fire.
Example:
Show a loading message whenever an Ajax request starts (and none is already active).
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