Hi Priyank,
Please have a look into the sample code snippet to achieve your scenario.
ASPX:
<
telerik:RadListBox
ID
=
"RadListBox1"
runat
=
"server"
SelectionMode
=
"Multiple"
OnClientSelectedIndexChanging
=
"OnClientSelectedIndexChanging1"
>
<
Items
>
<
telerik:RadListBoxItem
Text
=
"Item1"
/>
<
telerik:RadListBoxItem
Text
=
"Item2"
/>
<
telerik:RadListBoxItem
Text
=
"Item3"
/>
</
Items
>
</
telerik:RadListBox
>
JavaScript:
<script type=
"text/javascript"
>
function
OnClientSelectedIndexChanging1(sender, args) {
if
(args.get_item().get_selected())
args.get_item().set_selected(
true
);
}
</script>
Hope this will helps you.
Thanks,
Shinu.