<html><head> <title>Button Example</title> <script type="text/javascript" src="/upload/files/201702/EventUtil.js"></script></head><body> <div id="myDiv" style="background-color:red;height:100px;width:100px">Click me</div> <script type="text/javascript"> var div = document.getElementById("myDiv"); EventUtil.addHandler(div, "mousedown", function(event){ event = EventUtil.getEvent(event); alert(EventUtil.getButton(event)); }); </script></body></html>