JavaScript에는 몇 가지 데이터 유형이 있습니까? JavaScript에서 데이터 유형을 결정하는 방법

var a = "iamstring.";
var b = 222;
var c= [1,2,3];
var d = new Date();
var e = function(){alert(111);};
var f = function(){this.name="22";};

alert(typeof a)   ------------> string
alert(typeof b)   ------------> number
alert(typeof c)   ------------> object
alert(typeof d)   ------------> object
alert(typeof e)   ------------> function
alert(typeof f)   ------------> function

alert(typeof a == "string") -------------> true
alert(typeof a == String) ---------------> false

alert(c instanceof Array) ---------------> true
alert(d instanceof Date)
alert(f instanceof Function) ------------> true
alert(f instanceof function) ------------> false

alert(c.constructor == Array) ----------> true
alert(d.constructor == Date) -----------> true
alert(e.constructor == Function) -------> true

function A(){};
function B(){};
A.prototype = new B(); //A继承自B
var aObj = new A();
alert(aobj.constructor === B) -----------> true;
alert(aobj.constructor === A) -----------> false;

alert(aobj instanceof B) ----------------> true;
alert(aobj instanceof B) ----------------> true;

aobj.constructor = A; //将自己的类赋值给对象的constructor属性
alert(aobj.constructor === A) -----------> true;
alert(aobj.constructor === B) -----------> false; //基类不会报true了;

alert(Object.prototype.toString.call(a) === ‘[object String]’) -------> true;
alert(Object.prototype.toString.call(b) === ‘[object Number]’) -------> true;
alert(Object.prototype.toString.call(c) === ‘[object Array]’) -------> true;
alert(Object.prototype.toString.call(d) === ‘[object Date]’) -------> true;
alert(Object.prototype.toString.call(e) === ‘[object Function]’) -------> true;
alert(Object.prototype.toString.call(f) === ‘[object Function]’) -------> true;