Пересечение массива на основе функции

const intersection = (a, b) => {
  const s = new Set(b);
  return […new Set(a)].filter(x => s.has(x));
};

const intersectionWith = (a, b, comp) =>
  a.filter(x => b.findIndex(y => comp(x, y)) !== -1);

const intersectionBy = (a, b, fn) => {
  const s = new Set(b.map(fn));
  return […new Set(a)].filter(x => s.has(fn(x)));
};

intersection([1, 2, 3], [4, 3, 2]); // [2, 3]

intersectionWith(
  [1, 1.2, 1.5, 3, 0],
  [1.9, 3, 0, 3.9],
  (a, b) => Math.round(a) === Math.round(b)
); // [1.5, 3, 0]

intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [2.1]
intersectionBy(
  [{ title: 'Apple' }, { title: 'Orange' }],
  [{ title: 'Orange' }, { title: 'Melon' }],
  x => x.title
); // [{ title: 'Orange' }]