'onBeforeUnload' Example
<head>
<script language="JavaScript">
function function1() {
self.close()
}
function function2() {
window.open("http://www.java2s.com/", "", "width=300, height=200, left=200, noresize, top=200")
}
</script>
</head>
<body onbeforeunload="function2()">
<input type="button" value="Unload the document" onclick="function1()">
</body>
</html>