JS: Set Union, Intersection, Difference 📜

Set Union, Intersection, Difference

They are added in JS2024.

• JS: Set.prototype.union
• JS: Set.prototype.intersection
• JS: Set.prototype.difference

Union of Sets

/*
return a union of all sets.
Does not modify args.
Version: 2016-11-18
 */
const xah_set_union = (...sets) => {
  let X = new Set();
  sets.forEach((S) => S.forEach((e) => X.add(e)));
  return X;
};

// HHHH------------------------------

// test
let s1 = new Set([3, 4, 5]);
let s2 = new Set([5, 6]);
let s3 = new Set([11, 12]);
console.log(xah_set_union(s1, s2, s3));
// Set { 3, 4, 5, 6, 11, 12 }

Intersection of Sets

/*
return the intersection of all sets.
Does not modify args.
Version: 2016-11-18
*/

const xah_set_intersection = (...sets) =>
  sets.reduce(
    (A, B) => {
      let X = new Set();
      B.forEach((v) => {
        if (A.has(v)) X.add(v);
      });
      return X;
    },
  );

// HHHH------------------------------

// test
let s1 = new Set([3, 6, 4, 5]);
let s2 = new Set([6, 3]);
let s3 = new Set([11, 6, 12, 3]);
console.log(xah_set_intersection(s1, s2, s3));
// Set { 6, 3 }

Difference of Sets

/*
return the difference of all sets.
That is, A - B - C - D ....
Does not modify args.
Version: 2016-11-18
*/
const xah_set_difference = (...sets) =>
  sets.reduce(
    (A, B) => {
      let X = new Set(A);
      B.forEach((v) => {
        if (X.has(v)) X.delete(v);
      });
      return X;
    },
  );

// HHHH------------------------------

// test
let s1 = new Set([3, 4, 5, 6]);
let s2 = new Set([5, 3]);
let s3 = new Set([4]);
console.log(xah_set_difference(s1, s2, s3));
// Set { 6 }