js进行类型判断 Object.prototype.toString.call()

这篇文章主要讲解 js进行类型判断 Object.prototype.toString.call()

首先看一段ECMA中对Object.prototype.toString的解释：
Object.prototype.toString( )
When the toString method is called, the following steps are taken:

1. Get the [[Class]] property of this object.
2. Compute a string value by concatenating the three strings “[object “, Result (1), and “]”.
3. Return Result (2)

   var oP = Object.prototype,
   toString = oP.toString;
    
   console.log(toString.call([123]));//[object Array]
   console.log(toString.call('123'));//[object String]
   console.log(toString.call({a: '123'}));//[object Object]
   console.log(toString.call(/123/));//[object RegExp]
   console.log(toString.call(123));//[object Number]
   console.log(toString.call(undefined));//[object Undefined]
   console.log(toString.call(null));//[object Null]