<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<input type="button" value="button" id="button" onclick="show()">
<input type="button" value="button2" id="bt2">
<script type="text/javascript">
function show (){
alert("hello");
}
var b=Document.getElementById('bt2');
b.onclick=function(){
alert("这是通过DOM0级添加的事件");
}
// b.onclick=null;
</script>
</body>
</html>
注意大小写啊同学
var b=Document.getElementById('bt2');
哦哦，thanks