js数组排序 多条件

按照【次数】和【时间】排序，选择次数最多的排在前面，同样次数的情况下时间较新排在前面。

原始数据：

 var arr= [
     {name:'qqq', num:2,time:'2015-06-08 13:44:18'},
     {name:'www', num:3,time:'2015-06-08 13:44:18'},
     {name:'eee', num:4,time:'2015-06-07 13:40:18'},
     {name:'rrr', num:4,time:'2015-06-08 13:44:18'},
    {name:'yyy', num:6,time:'2015-06-07 13:40:18'},
 ];

排序后的数据：

 arr= [
     {name:'yyy', num:6,time:'2015-06-07 13:40:18'},
     {name:'rrr', num:4,time:'2015-06-08 13:44:18'},
     {name:'eee', num:4,time:'2015-06-07 13:40:18'},
     {name:'www', num:3,time:'2015-06-08 13:44:18'},
     {name:'qqq', num:2,time:'2015-06-08 13:44:18'}
 ];

代码实现：

 arr.sort(function(a, b){
     if (a.num === b.num) {
         return new Date(b.time.replace(/-/g, "/")) - new Date(a.time.replace(/-/g, "/"))
     } else {
         return b.num - a.num;
     }
 });