Calling a JavaScript function of Parent Window from Child Window

Code in Parent Page

<script type="text/javascript">
   function openChildWindow() {
       window.open('UrlToOpen', 'mywindow1234567890');
       window.CallParentfunction= function () {
         //Your Code Functionality
       }
    }
</script>

<a onclick="openChildWindow(); return false;">Open Child Window</a>

Code in Child Page

 

Calling Function of Parent Window in Child Window:

<script type="text/javascript">
     window.onunload = function (e) {
     opener.CallParentfunction();
     };
</script>

Note: This doesn't work on IE if the the Child window and the Parent window are not from the same domain.