​x
 
<!DOCTYPE html>
<html>
<body>
​
<p>typeof 运算符返回变量、对象、函数或表达式的类型。</p>
​
<p id="demo"></p>
​
<script>
document.getElementById("demo").innerHTML = 
  typeof "Bill" + "<br>" +
  typeof 3.14 + "<br>" +
  typeof NaN + "<br>" +
  typeof false + "<br>" +
  typeof [1, 2, 3, 4] + "<br>" +
  typeof {name:'Bill', age:19} + "<br>" +
  typeof new Date() + "<br>" +
  typeof function () {} + "<br>" +
  typeof myCar + "<br>" +
  typeof null;
</script>
​
</body>
</html>
​