js检测数据类型的方法你都掌握了几个？

数据类型检测

 typeof检测
 var obg = {};
 var ary = [];
 var reg = /^$/;
 var fn = function () {};
 var num = 1;
 var bool = true;
 var nul = null;
 var undef = undefined;
 var str = "";
 console.log(typeof obg);//"object"
 console.log(typeof ary);//"object"
 console.log(typeof num);//"number"
 console.log(typeof reg);//"object"
 console.log(typeof fn);//"function"
 console.log(typeof bool);//"boolean"
 console.log(typeof nul);//"object"
 console.log(typeof undef);//"undefined"
 console.log(typeof str);//"string"*/

typrof不能具体细分是正则、数组、null、对象，因为用typeof检测的时候结果都是"object"

2、instanceof检测，只要在实例的原型链上检测出来的结果都是true

 var num = 1;字面量方式创建
 console.log( 1 instanceof Number); ->false
 var num = new Number(1);实例方式创建
 console.log( num instanceof Number);->true
 var ary = [];
 console.log(ary instanceof Array);->true
 console.log(ary instanceof Object);->true
 var fn = function () {};
 console.log(fn instanceof Function);->true
 console.log(fn instanceof Object);->true

 var num = 1;字面量方式创建
 console.log( 1 instanceof Number); ->false
 var num = new Number(1);实例方式创建
 console.log( num instanceof Number);->true
 var ary = [];
 console.log(ary instanceof Array);->true
 console.log(ary instanceof Object);->true
 var fn = function () {};
 console.log(fn instanceof Function);->true
 console.log(fn instanceof Object);->true

3、constructor 构造函数可以处理基本数据类型检测

     var ary = [];
     console.log( ary.constructor === Array);
     var num = 1;
     console.log(num.constructor === Number)

4、Object.prototype.toString.call最准确最常用的方法

     var ary = [];
     var reg = /^$/;
     var fn = function () {};
     var num = 1;
     var bool = true;
     console.log(Object.prototype.toString.call(ary));->[object Array]
     console.log(Object.prototype.toString.call(reg));->[object RegExp]
     console.log(Object.prototype.toString.call(fn));->[object Function]
     console.log(Object.prototype.toString.call(num));->[object Number]
     console.log(Object.prototype.toString.call(bool));->[object Boolean]