Array union based on function

OSCC · JavaScript, Array · Oct 22, 2020

Returns every element that exists in any of the two arrays at least once, using a provided comparator function.

  • Create a Set with all values of a and values in b for which the comparator finds no matches in a, using Array.prototype.findIndex().
const unionWith = (a, b, comp) =>
  Array.from(
    new Set([...a, ...b.filter(x => a.findIndex(y => comp(x, y)) === -1)])
  );
unionWith(
  [1, 1.2, 1.5, 3, 0],
  [1.9, 3, 0, 3.9],
  (a, b) => Math.round(a) === Math.round(b)
);
// [1, 1.2, 1.5, 3, 0, 3.9]

Recommended snippets

  • Mapped array union

    JavaScript, Array

    Returns every element that exists in any of the two arrays at least once, after applying the provided function to each array element of both.

  • Returns the elements that exist in both arrays, using a provided comparator function.

  • Array union

    JavaScript, Array

    Returns every element that exists in any of the two arrays at least once.