基本數(shù)據(jù)類型

Number、String、null、undefined、boolean

引用數(shù)據(jù)類型

Object、function、Array、RegExp、new Date、 Math 實例對象。。。 function

es6新增數(shù)據(jù)類型

Synbol

其他

NaN

檢測數(shù)據(jù)類型

var fn = funcion(){};
var obj = {};
var num = 1；

1. typeof
   typeof NaN => "number"
   typeof null =>"object"
   typeof 2 => "number"
   typeof "aa" => "string"
   typeof fn => "function"
   typeof obj => "object"
2. instanceof
   "aa" instanceof String => true
   fn instanceof Function => true
   obj instanceof Object => true
   1 instanceof Number => false
   number instanceof Number => false;
   NaN instanceof NaN => TypeError: Right-hand side of 'instanceof' is not an object
   false instanceof Boolean => false
   3.toString
   Object.prototype.toString.call('') ; // [object String]
   Object.prototype.toString.call(1) ; // [object Number]
   Object.prototype.toString.call(true) ; // [object Boolean]
   Object.prototype.toString.call(Symbol()); //[object Symbol]
   Object.prototype.toString.call(undefined) ; // [object Undefined]
   Object.prototype.toString.call(null) ; // [object Null]
   Object.prototype.toString.call(new Function()) ; // [object Function]
   Object.prototype.toString.call(new Date()) ; // [object Date]
   Object.prototype.toString.call([]) ; // [object Array]
   Object.prototype.toString.call(new RegExp()) ; // [object RegExp]
   Object.prototype.toString.call(new Error()) ; // [object Error]
   Object.prototype.toString.call(document) ; // [object HTMLDocument]
   Object.prototype.toString.call(window) ; //[object global] window 是全局對象 global 的引用