<!DOCTYPE html>
<html>
<body>
<h2>JavaScript typeof</h2>
<p>typeof 运算符返回变量或表达式的类型：</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML =
typeof "" + "<br>" +
typeof "Bill" + "<br>" +
typeof "Bill Gates";
</script>
</body>
</html>