[JavaScript] Two sum

two-sum.js

const assert = require('assert');

function twoNumberSum(array, targetSum) {
  // Hold the difference,
  const memo = {};
  let result = [];
  // Use .some higher order function for break the loop when found.
  // You can prefer basic for loop with `break`
  array.some(num => {
    // We will find the pair in this object.
    /**
     * memo = { [10 - 11]: 11 } // -1 is the right pair for hitting the target.
     */
    // When the `-1` came to te que, we already now, -1 and 11 is pair for target.
    if (memo[num] !== undefined) {
      // I found the pairs,
      result = [num, memo[num]];
      // Break the loop.
      return true;
    }
    /*
      memo = {
        [10 - 3]: 3 // 7: 3, In here, 7 is the right pair for hitting the target.
      }
    */
    memo[targetSum - num] = num;
  })
  return result;
}

assert.deepStrictEqual(twoNumberSum([3, 5, -4, 8, 11, 1, -1, 6], 10), [-1, 11])