Disable the Button & Prevent from Multiple submits

<script type="text/javascript">    

// for issue of multiple submits 
 var Count = 0;
 function DisableButton() 
 {  
   if (Count == 0)
   {  
     Count = 1;     // alert(window.document.readyState);
     return true;
   }
   else
   {
     Count += 1;    // alert(window.document.readyState);
    return false;
   }
}  
</script>
  
      ibtnSubmit.OnClientClick = "return DisableButton();"    return false;</script>