如何判断数组或者对象

var arr = ['1', '2', '3'];

var obj = {

    'a': '1',

    'b': '2', 

     'c': '3

 };

1、instanceof

console.log(arr instanceof Array); // true

console.log(arr instanceof Object); // true

2、constructor

console.log(arr.constructor === Array); // true

console.log(obj.constructor === Object); // true

3、Object.prototype.toString.call()

var res = Object.prototype.toString.call(arr);

console.log(res);  // [object Array]

var res2 = Object.prototype.toString.call(obj);

console.log(res2);  / /[object Object]

4、Array.isArray()