30-seconds-of-code/snippets/symmetricDifferenceWith.md

title, tags, expertise, cover, firstSeen, lastUpdated

title	tags	expertise	cover	firstSeen	lastUpdated
Array symmetric difference	array	intermediate	blog_images/digital-nomad.jpg	2018-01-24T11:59:02+02:00	2020-10-18T14:58:09+03:00

Returns the symmetric difference between two arrays, using a provided function as a comparator.

• Use Array.prototype.filter() and Array.prototype.findIndex() to find the appropriate values.

const symmetricDifferenceWith = (arr, val, comp) => [
  ...arr.filter(a => val.findIndex(b => comp(a, b)) === -1),
  ...val.filter(a => arr.findIndex(b => comp(a, b)) === -1)
];

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