JS使用typeof判断类型

1 console.log(typeof 2); // number
2 console.log(typeof "2"); // string
3 console.log(typeof true); // boolean
4 console.log(typeof [2]); //  
5 console.log(typeof {name:2});//  
6 console.log(typeof function(){return 2});// function
7 console.log(typeof new Date());//  
8 console.log(typeof null); //  
9 console.log(typeof undefined);// undefined

 1 var getType =  .prototype.toString;
 2 var res = getType.call(2);
 3 res = getType.call("2");
 4 res = getType.call(true);
 5 res = getType.call([2]);
 6 res = getType.call({name:2});
 7 res = getType.call(function(){});
 8 res = getType.call(new Date());
 9 res = getType.call(null);
10 res = getType.call(undefined);

1 [  Number]
2 [  String]
3 [  Boolean]
4 [  Array]
5 [   ]
6 [  Function]
7 [  Date]
8 [  Null]
9 [  Undefined]