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]