Hello SriRam,
Here are a few resources:
http://aspalliance.com/716_Populating_a_DropDownList_using_AJAX_and_ASPNET.4
http://roshanbh.com.np/2008/09/change-textbox-value-dropdown-list-ajax-php.html
http://www.w3schools.com/HTMLDOM/prop_option_value.asp
This last one here is the code:
<html>
<head>
<script type="text/javascript">
function alertValue()
{
var x=document.getElementById("mySelect").selectedIndex;
alert(document.getElementsByTagName("option")[x].value);
}
</script>
</head>
<body><form>
Select your favorite fruit:
<select id="mySelect">
<option value="apple">Apple</option>
<option value="orange">Orange</option>
<option value="pineapple">Pineapple</option>
<option value="banana">Banana</option>
</select>
<br /><br />
<input type="button" onclick="alertValue()"
value="Alert selected value">
</form></body>
</html>
The main idea for getting any value in AJAX- is to raise an event on a control, and have a function it calls. The main element for getting access to the control is GetElementBy...
Any other questions let me know,
Jeremy
Please mark post if this helped, so as to help others - Thanks