                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /DOM事件探秘

在我電腦上測試不通過，在chrome和ie8都是在dom0級

<!DOCTYPE?html>
<html>
<head>
???<meta?charset="UTF-8">
???<title></title>
</head>
<body>
<div>
???<input?type="button"?id="btn3"?value="按鈕3">
</div>
<script>
???function?showMsg(){
???????alert('Hello?world!');
???}
???//browser?compatible
var?eventUtil={
???????//add?handler
addHandler:function(element,type,handler){
???????????if(element.addEventListener){
???????????????//dom2?level
element.addEventListener(type,handler,false);
???????????}else?if(element.attachEvent){
???????????????//ie
element.attachEvent('on'+type,handler);
???????????}else{
???????????????//dom0?level
???????????????//在js中所有用.連接屬性的時候都可以用[]，element.onclick?===?element['onclick']
element['on'+type]?=?handler;
???????????}
???????},
???????//remove?handler
removeHandler:function(element,type,handler){
???????????if(element.removeEventListener){
???????????????element.removeEventListener(type,handler,false);
???????????}else?if(element.detachEvent){
???????????????element.detachEvent('on'+type,handler);
???????????}else{
???????????????element['on'+type]?=?null;
???????????}
???????}
???};
???//call?object
eventUtil.addHandler('btn3','click',showMsg);
???//eventUtil.removeHandler('btn3','click',showMsg);
</script>
</body>
</html>