JS notes data type judgment

I came across an article today  typeof and instanceof The difference between  , At the end of the article

console.log(Number instanceof Number);//false 
console.log(String instanceof String);//false 

It's a bit of a mystery , I was thinking Number and String Why not instanceof What about themselves ？？？ Just a test Number What is it , As a result, they themselves are Function！！ Good! , Think about it, too , It can new, Create an instance or something

Object yes function, It turned out Function It's also Object, therefore Number and String It's also Object example , as follows ：

typeof Object
// 'function'

Object instanceof Function
// true

Object instanceof Object
// true

Function instanceof Function
// true

Function instanceof Object
// true

String instanceof Object
// true

To sum up , Several data types are judged ：

1.typeof  You can judge simple data types , It doesn't work for complex data types ;

2.instanceof It is mainly used to judge complex data types （ Determine whether the current object is an instance of another object ） Returns a Boolean value ;

3.Object.prototype.toStringcall() Can accurately judge all data types ;

4.constructor Be able to judge multiple data types , and instanceof almost （null and undefined With the exception of ）

I wrote this before , You can go and have a look ： JS- Cycle to empty objects && Determine the type of data 5 A common way