set-basic-method.js

/* Source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set#implementing_basic_set_operations */

function isSuperset(set, subset) {
  for (const elem of subset) {
    if (!set.has(elem)) {
      return false;
    }
  }
  return true;
}

function union(setA, setB) {
  const _union = new Set(setA);
  for (const elem of setB) {
    _union.add(elem);
  }
  return _union;
}

function intersection(setA, setB) {
  const _intersection = new Set();
  for (const elem of setB) {
    if (setA.has(elem)) {
      _intersection.add(elem);
    }
  }
  return _intersection;
}

function symmetricDifference(setA, setB) {
  const _difference = new Set(setA);
  for (const elem of setB) {
    if (_difference.has(elem)) {
      _difference.delete(elem);
    } else {
      _difference.add(elem);
    }
  }
  return _difference;
}

function difference(setA, setB) {
  const _difference = new Set(setA);
  for (const elem of setB) {
    _difference.delete(elem);
  }
  return _difference;
}

// Examples
const setA = new Set([1, 2, 3, 4])
const setB = new Set([2, 3])
const setC = new Set([3, 4, 5, 6])

isSuperset(setA, setB)          // returns true
union(setA, setC)               // returns Set {1, 2, 3, 4, 5, 6}
intersection(setA, setC)        // returns Set {3, 4}
symmetricDifference(setA, setC) // returns Set {1, 2, 5, 6}
difference(setA, setC)          // returns Set {1, 2}