SOURCE

let nums = [2,7,11,15],target = 0;
var twoSum = function(nums,target){
  let map = new Map();
  for(let i = 0;i<nums.length;i++){
    let diff = target-nums[i]
    console.log('diff',diff)
    if(map.has(diff)){
      return [map.get(diff),i]
    }
    map.set(nums[i],i)
  }
  console.log('map',map)
}
twoSum(nums,target)