下面代码这里为什么alert弹不出来?
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>我们互动下</title>
<script type="text/javascript">
function jump(){
var mymessage=confirm("JS进阶篇");
if(mymessage==true){
alert("关注JS高级篇");
}
else{
null;
}
}
</script>
</head>
<body>
<form>
<input type="buttom" value="点击这儿" onclick="jump()"/>
</form>
</body>
</html>