How to determine whether it is an object in javascript

Judgment method: 1. Use toString() to judge; 2. Use "obj.constructor === Object" to judge; 3. Use "ypeof obj === Object" to judge; 4. Use instanceof keyword to judge.

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

1. toString() first choice

let obj = {}
Object.prototype.toString.call(obj) === '[Object Object]'

2. constructor

let obj = {}
obj.constructor === Object

【Recommended learning: js basic tutorial】

3. instanceof

Attention : Using instanceof to judge an array is also an object

let obj = {}
obj instanceof Object  //true
let arr = []
arr instanceof Object  //true

4, typeof

let obj = {}
typeof obj === Object
// 根据typeof判断对象也不太准确
表达式                       返回值
typeof undefined           'undefined'
typeof null                'object'
typeof true                'boolean'
typeof 123                 'number'
typeof "abc"               'string'
typeof function() {}       'function'
typeof {}                  'object'
typeof []                  'object'

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