twosum.js

function twoSum(numArray, sum) {
  var pairs = [];
  var hashTable = [];
 
  for (var i = 0; i < numArray.length; i++) {
    var currNum = numArray[i];
    var counterpart = sum - currNum;
    if (hashTable.indexOf(counterpart) !== -1) {
      pairs.push([ currNum, counterpart ]);
    }
    hashTable.push(currNum);
  }
  
  return pairs;
}