1.typeof
其他（数字Number，布尔值Boolean，字符串String，函数Function，对象Object，Undefined）这一些数据类型在typeof 下都被精准的解释，只有数组和null的数据类型不够精准。
console.log(typeof 2); // number
console.log(typeof true); // boolean
console.log(typeof 'str'); // string
console.log(typeof []); // object []数组的数据类型在 typeof 中被解释为
console.log(typeof function(){}); // function
console.log(typeof {}); // object
console.log(typeof undefined); // undefined
console.log(typeof null);
2.instanceof
只有引用数据类型（Array，Function，Object）被精准判断
console.log(2 instanceof Number); // false
console.log(true instanceof Boolean); // false
console.log('str' instanceof String); // false
console.log([] instanceof Array); // true
console.log(function(){} instanceof Function); // true
console.log({} instanceof Object);
3.constructor
console.log((2).constructor === Number);
console.log((true).constructor === Boolean);
console.log(('str').constructor === String);
console.log(([]).constructor === Array);
console.log((function() {}).constructor === Function);
console.log(({}).constructor === Object);
4.Object.prototype.toString.call
最靠谱
var a = Object.prototype.toString;
console.log(a.call(2));
console.log(a.call(true));
console.log(a.call('str'));
console.log(a.call([]));
console.log(a.call(function(){}));
console.log(a.call({}));
console.log(a.call(undefined));
console.log(a.call(null));
参考 ：https://blog.csdn.net/zjy_android_blog/article/details/81023177