//typeof 检测变量是什么类型的
//在控制台输出类型的名称
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie-edge">
<title>Document</title>
<script>
var num = 10 ;
console.log(typeof num);//number 数字型
var str = 'pink' ;
console.log(typeof str);//string 字符型
var flag = true ;
console.log(typeof flag);//boolean 布尔型
var vari = undefined ;
console.log(typeof vari);//undefined
var timer = null ;
console.log(typeof timer);//object
//prompt 去过来的值是字符型的 string 也就是不能进行一些运算
var age = prompt('请输入您的年龄');
console.log(typeof age);//这里从prompt里面取出来的值是字符类型的 string
</script>
</head>
<body>
</body>
</html>
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