How to trigger a client side event for a combobox dropdown selection

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I am using an Ajaxtoolkit ComboBox in a webform page and I need to check if the user has selected (click on) a drop down value other than the one displayed. I need to do this client side. Is there any way of adding a javascript function which will trigger when the dropdown value is changed. The SelectedIndexChanged event does not trigger until postback which is no good.

here is the code from the project

<br />
<ajaxToolkit:ComboBox ID="ComboBox1" runat="server" AutoPostBack="false"   OnSelectedIndexChanged="ComboBox1_SelectedIndexChanged" >
</ajaxToolkit:ComboBox>
 <br />

public void Page_Load(object sender, EventArgs e)
        {
            ComboBox1.Items.Add("Test Item 1");
            ComboBox1.Items.Add("Test Item 2");
            ComboBox1.Items.Add("Test Item 3");
        }

        public void ComboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
        }

appreciate any advise on how to achieve this

What I have tried:

searched for examples - but found none. Tried adding an eventlistner but did not work.

Posted 14-Jul-17 9:43am

PClarkeirl

Updated 16-Jul-17 20:12pm

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Vikas Shirsath · Answer 1 · 2017-07-16T20:12:00

<script type="text/javascript" language="javascript">
function SetAllCheckBoxes(FormName, AreaID, CheckValue)
{
if(!document.forms[FormName])
return;
var objCheckBoxes = document.getElementById(AreaID).getElementsByTagName('input');
if(!objCheckBoxes)
return;
var countCheckBoxes = objCheckBoxes.length;
if(!countCheckBoxes)
objCheckBoxes.checked = CheckValue;
else
for(var i = 0; i < countCheckBoxes; i++)
objCheckBoxes[i].checked = CheckValue;
}
</script>