Leetcode 1. 两数之和 js

js版

var twoSum = (arr, target) => {
    let map = new Map(), res = [];
    arr.forEach((item,index) => {
      const map_index = map.get(target - item);
      if(map_index !== undefined){
        res = [map_index, index]
      }else {
        map.set(item, index)
      }
    });
    return res;
  };