JS 一个函数处理多个事件

<script type="text/javascript">window.onload = function() {//this指向注册这个事件元素/**document.getElementById("testBtn").onclick = function(event) {alert(event);alert(event.target);alert(this);alert(event.currentTarget);alert(this === event.currentTarget);} */var btnNode = document.getElementsByTagName("input").item(0);var handler = function(event) {switch (event.type) {case "click":alert("clicked");break;case "mouseover":event.currentTarget.style.backgroundColor = "red";break;case "mouseout":event.currentTarget.style.backgroundColor = "";break;}};btnNode.onclick = handler;btnNode.onmouseover = handler;btnNode.onmouseout = handler;};</script>