1 var arr = [];
2 console.log(Array.isArray(arr));//true

 1 //检测各种数据类型的方法
 2 var is = { types : ["Array", "Boolean", "Date", "Number", "Object", "RegExp", "String", "Window", "HTMLDocument"] } ；
 3 
 4 for(var i=0,c;c=is.types[i++];){
 5     is[c]=(function(type){
 6         return function(obj){
 7             return Object.prototype.toString.call(obj) == "[object" +     type + "]";
 8         }
 9     })(c);
10 }
11 
12 var arr = [1,2,3];
13 var str = ‘123‘;
14 var num = 123;
15 var a = true;
16 var b = new Date();
17 var obj = new Object();
18 var c = new RegExp(/0-9/ig);
19 
20 console.log(is.Array(arr));//true
21 console.log(is.String(str));//true
22 console.log(is.Number(num));//true
23 console.log(is.Boolean(a));//true
24 console.log(is.Date(b));//true
25 console.log(is.Object());//true
26 console.log(is.RegExp(c));//true
27 console.log(is.Window(window));//true
28 console.log(is.HTMLDocument(document));//true