window.onbeforeunload = onbeforeunload_handler;
window.onunload = onunload_handler;
function onbeforeunload_handler(){
var warning="确认退出?"; return warning;
}
function onunload_handler(){
var warning="谢谢光临"; alert(warning);
}
原文：http://www.cnblogs.com/jok311/p/6802290.html