<html>
<head>
<script type="text/javascript" src="common.js">
document.write("inner");
</script>
<script type="text/javascript">
var x=1;
var str01='abc';
var str02="def";
//alert(typeof x);
alert(typeof str01);
//console.log(typeof x);
</script>
</head>
<body>
</body>
</html>
首先在js中""和‘’是没有区别的，typeof能返回该对象的类型