Making An Ajax Request On Mouse Key Up On A Text Field

Hi,

I need to make an ajax request on keypress event on a page , although I am able to make ajax request on Ajaxlink and onchange event of a drop down , but in case of making a request on key press event on a text field I am not having any clue, I am writing the code for onchange event as follows

[color="#8B0000"]<?php

echo CHtml::dropDownList(‘function_parent’,’’,MasterData::getClassification(),

			array(


					'ajax' =&gt; array(


							'type'=&gt;'POST',


							'url'=&gt;CController::createUrl('cand/getcndchield'),


							'success'=&gt;'js:function(data){&#036;(&quot;#function_id&quot;).html(data);


                            &#036;(&quot;#function_id&quot;).show();

}’,

					)));


	 ?&gt;[/color]

Can anyone help me out .