[LeetCode] Two Sum

Description:

Given an array of integers, return indices of the two numbers such that they add up to a specific target.
You may assume that each input would have exactly one solution, and you may not use the same element twice.
Example:
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

MySolution:

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    var map = {}, i, len, cur;
    for(i = 0, len = nums.length; i < len; i+=1) {
        cur = nums[i];
        if(typeof map[cur] === 'undefined') {
            map[target - cur] = i;
        } else {
            return [map[cur], i];
        }
    }
};

Runtime: 60ms