常见的检测数据类型的几种方式

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我是靠谱客的博主饱满水池，最近开发中收集的这篇文章主要介绍常见的检测数据类型的几种方式，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1、typof

使用时直接 typeof 要检测的类型值
对于引用类型只可以检测出object（包括不同对象、数组、正则、日期等等）、function也就是说不管对象类型具体为什么类型都显示为 object
typeof 可以检测number、string、boolean、null、undefined、symbol这些基本类型值
type of只能检测数基本数据类型，不能检测引用数据类型和null
关于typeof的一些细节：
返回的结果都是字符串，还有对于null的检测结果也为object

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
var str = '蛤蛤'
var num =1
var bol = true
var und
var obj ={name:'蛤蛤'}
console.log(typeof(str));
console.log(typeof(num));
console.log(typeof(bol));
console.log(typeof(und));
console.log(obj);
</script>
</html><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
var str = '蛤蛤'
var num =1
var bol = true
var und
var obj ={name:'蛤蛤'}
console.log(typeof(str));
console.log(typeof(num));
console.log(typeof(bol));
console.log(typeof(und));
console.log(obj);
</script>
</html>

2，instanceof

除了使用typeof来判断还可以使用instanceof。instanceof运算符需要指定一个构造函数，或者说指定一个特定的类型，它用来判断这个构造函数的原型是否在给定队形的原型链上。

基本数据类型中number，string，Boolean。字面量值不可以用instanceof检测但是构造函数创建的值可以

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
var num = new Number(123);
var str = new String('dsfsf');
var bol = new Boolean(false);
console.log(num instanceof Number);
console.log(str instanceof String);
console.log(bol instanceof String);
</script>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
console.log(
100 instanceof Number, //false
'dsfsf' instanceof String, //false
false instanceof Boolean, //false
undefined instanceof Object, //false
null instanceof Object, //false
[1, 2, 3] instanceof Array, //true
{ a: 1, b: 2, c: 3 } instanceof Object, //true
function () { console.log('aaa'); } instanceof Function, //true
new Date() instanceof Date, //true
/^[a-zA-Z]{5,20}$/ instanceof RegExp, //true
new Error() instanceof Error //true
)
</script>
</html>

3，Object.prototype.toString.call(）

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
var str ='蛤蛤'
var num =1
console.log(Object.prototype.toString.call(str).slice(8,-1));
console.log(Object.prototype.toString.call(num).slice(8,-1));
</script>
</html>