[LeetCode][JavaScript]Contains Duplicate II

 1 /**
 2  * @param {number[]} nums
 3  * @param {number} k
 4  * @return {boolean}
 5  */
 6 var containsNearbyDuplicate = function(nums, k) {
 7     var map = {};
 8     for(var i in nums){
 9         if(map[nums[i]] !== undefined){
10             if(Math.abs(map[nums[i]] - i) <= k){
11                 return true;
12             }
13         } else {
14             map[nums[i]] = i;
15         }
16     }
17     return false;
18 };