关于js数组的一道小考题

 1         var arr = [2,3,[4,6,[3,8,[15,16,[17,18,[1,2,3,[19,20]]]]],[13,14],[5,6,7,11,9]],12,10];
 2         var NumArr = [];
 3         function isType (obj, type) {//判断类型
 4             return Object.prototype.toString.call(obj).indexOf(‘[object ‘ + type) == 0;
 5         }
 6         function sortNum(a,b){//升序
 7             return a - b;
 8         }
 9         function getArray(arr) {//去重
10             var hash = {},
11                 len = arr.length,
12                 result = [];
13             for (var i = 0; i < len; i++){
14                 if (!hash[arr[i]]){
15                     hash[arr[i]] = 1;
16                     result.push(arr[i]);
17                 } 
18             }
19             return result;
20         }
21         function pick(o){
22             for(var n = 0, len = o.length; n<len; n++){
23                 if(isType(o[n],"Number")){
24                     NumArr.push(o[n]);
25                 } else {
26                     arguments.callee(o[n]);
27                 }
28             }
29         }
30         function part(o){//分发判断数组里的每个类型
31             if(isType(o,"Number")){
32                 NumArr.push(o);
33             } else {
34                 pick(o);
35             }
36         }
37         for(var i = 0,l = arr.length; i<l; i++){
38             part(arr[i]);
39         }        
40         NumArr = getArray(NumArr);//去重
41         document.write(NumArr.sort(sortNum));//排序输出 NumArr [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]