js的几种数据类型

javascript的几种基本类型：

1. null
2. undefined
3. Boolean
4. string
5. Number
6. Object

我看到网上一篇文章说是typeof无法判断function，可是为什么我试验了一下是可以判断的呢？不懂，欢迎各位看到有什么问题可以留言哦

var b=function(){console.log(999);}
typeof b
"function"
Object.prototype.toString.call(b)
"[object Function]"

 array:typeof无法判断array倒确实,用Obeject.prototype.toString.call()

var a=new Array(1,2,3);
undefined
a
[1, 2, 3]
typeof a
"object"
Object.prototype.toString(a);
"[object Object]"

null:

typeof null
"object"
Object.prototype.toString.call(null)
"[object Null]"

 Date:

var a=new Date()
undefined
a
Mon Aug 29 2016 14:11:45 GMT+0800 (CST)
typeof a
"object"
Object.prototype.toString.call(a)
"[object Date]"

 HTMLCollection:

var a=document.getElementsByTagName('div');
undefined
Object.prototype.toString.call(a)
"[object HTMLCollection]"