运行没结果，怎么回事？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>window对象</title>
<script type="text/javascript">
function myfun{
alert("点击我，弹出新窗口！");
window.open("http://www.imooc.com","_break","width=600,height=400 ");
}
</script>
</head>
<body>
<form>
<input type="button" value="点击我，打开新窗口" onclick="myfun()" />
</form>
</body>
</html>
