var obj={

    left:10,

    top:20

}

var arr=[1,2,3];

function Person(name){

    this.name=name;

}

var p1=new Person('kaivon');

console.log(obj);            //toString在它对应的原型身上

console.log(arr);            //toString在它对应的原型身上

console.log(p1);                //toString在Object身上

console.log(obj.toString());            //[object Object]

console.log(arr.toString());            //1,2,3

console.log(p1.toString());            //[object Object]

console.log(Person.toString());        //function Person(name{this.name=name;}

var num=0;

var str='kaivon';

var b=true;

var n=null;

var u=undefined;

var arr1=[];

var obj1={};

var fn=function(){};

var d=new Date();

var re=new RegExp();

//call可以改变this指向

console.log(Object.prototype.toString.call(num));        //[object Number]

console.log(Object.prototype.toString.call(str));        //[object String]

console.log(Object.prototype.toString.call(b));            //[object Boolean]

console.log(Object.prototype.toString.call(n));            //[object Null]

console.log(Object.prototype.toString.call(u));            //[object Undefined]

console.log(Object.prototype.toString.call(arr1));        //[object Array]

console.log(Object.prototype.toString.call(obj1));        //[object Object]

console.log(Object.prototype.toString.call(fn));            //[object Function]

console.log(Object.prototype.toString.call(d));            //[object Date]

console.log(Object.prototype.toString.call(re));            //[object RegExp]

//可以很精确判断出数据类型