return false; is NOT working [Resolved]

return false; is NOT working

Its a common error while handling logic operation in JavaScript.

Here i'm listing a few reason 

Here chkduplicate() is my function

1.IF you are calling a function on OnClientClick event try to use return before the function 

<asp:Button ID="btnSaveFileFormat" runat="server" Text="Save File Type" class="btn_cl" OnClientClick='return chkduplicate();'

                    Style="width: 195px; float: right" ValidationGroup="saveColumnDetails" OnClick="btnSaveFileFormat_Click" />

 2.     $(document).ready(function() {

           $('#<%= btnSaveFileFormat.ClientID%>').click(function(e) 

               if (chkduplicate() == false)

                e.preventDefault();

        });});

              Its better that first method
3.   

<form onsubmit="return chkduplicate();">

OR

<form action="JAVASCRIPT:chkduplicate();"

 4.if you are using nested function don't give return false at child function instead of that give that at parent function

If u had any trouble just ask, Happy to help u :) 
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Have a nice day... 'N happy Coding :)