Easy - Two Sum

https://leetcode.com/problems/two-sum/description/

Answer

var twoSum = function (nums, target) {
  let map = {};
  for (let i = 0; i < nums.length; i++) {
    const sum = target - nums[i];
    if (sum in map) {
      return [map[sum], i];
    } else {
      map[nums[i]] = i;
    }
  }
};