Calling javascript function when using update panel

Sometimes we come across situation that we want to call some javascript function from code inside update panel and javascript function didn't execute at all.In 
such situations we can use Script Manager class RegisterStartupScript Method
and it will easily call javascript function.

Eg:- 
ScriptManager
.RegisterStartupScript(Me.Page, Me.GetType(), "temp", 
"<script type='text/javascript'>
window.parent.document.getElementById('a2').style.display='none';
</script>", False)