Prevent LinkButton post back OnClientClick not working. Why?

Question

I know there are plenty of answers surrounding this topic but I just cannot get this to work.

I need to prevent a link button posting back and the following code is

Answer 1

Add Return statement in onClientClick Javascript Event

OnClientClick="return showConfirm(event);"

So when showConfirm return false then request will not be transer to server and page not postback.