const join = (leftTable, rightTable, direction) => {

  let tableOne;

  let tableTwo;

​

  if (direction.toLowerCase() === 'left') {

    tableOne = leftTable;

    tableTwo = rightTable;

  } else if (direction.toLowerCase() === 'right') {

    tableOne = rightTable;

    tableTwo = leftTable;

  } else { throw 'error, invalid join direction'; }

​

  const results = [];

  for (let i = 0; i < tableOne.buckets.length; i++) {

    const row = [];

    if (tableOne.buckets[i]) {

      const key = (Object.keys(tableOne.buckets[i].head.value)[0]);

      const value = (tableOne.buckets[i].head.value[key]);

      row[row.length] = key;

      row[row.length] = value;

      if (tableTwo.contains(key)) {

        row[row.length] = tableTwo.get(key);

      }

      else { row[row.length] = null; }

      results[results.length] = row;

    }

  }

  return results;

};