.on( "ajaxStart", handler )Returns: jQuery
Description: Register a handler to be called when the first Ajax request begins. This is an Ajax Event.
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version added: 1.7.on( "ajaxStart", handler )
This page describes the ajaxStart
event. For the deprecated .ajaxStart()
method, see .ajaxStart()
.
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 .on( "ajaxStart", ... )
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.
Additional Notes:
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As of jQuery 1.9, all the handlers for the jQuery global Ajax events, including those added with
.on( "ajaxStart", ... )
, must be attached todocument
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If
$.ajax()
or$.ajaxSetup()
is called with theglobal
option set tofalse
, theajaxStart
event will not fire.
Example:
Show a loading message whenever an Ajax request starts (and none is already active).
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