Outer Join of array in js using Map, Set, Array

outerJoinArray.js

const a = [
  { id: 3, name: 'Matt' },
  { id: 4, name: 'Greg' },
  { id: 1, name: 'David' },
  { id: 2, name: 'John' },
];
const b = [
  { id: 7, position: 'Outlier' },
  { id: 2, position: 'Leader' },
  { id: 3, position: 'Captain' },
  { id: 6, position: 'Rogue' },
  { id: 4, position: 'VP' },
  { id: 5, position: 'Pawn' },
];

function comparer(a, b) {
  if (a < b) {
    return -1;
  }
  if (a > b) {
    return 1;
  }
  return 0;
}
const tableA = new Map(a.map(item => [item.id, item]));
const tableB = new Map(b.map(item => [item.id, item]));

const ids = new Set(
  a
    .concat(b)
    .map(item => item.id)
    .sort(comparer),
);
const outerJoin = Array.from(ids.values()).map(item => {
  return {
    ...tableA.get(item),
    ...tableB.get(item),
  };
});
console.log(outerJoin);