JavaScript Program to Illustrate Different Set Operations

This article illustrates the various operations that can be applied in a set. There are various operations that can be applied on a set that are listed below:

• Union of sets
• Intersection of sets
• Set difference
• Set Subset Operation

Union of sets

A union set is the combination of two elements. In mathematical terms, the union of two sets is shown by A ∪ B. It means all the elements in set A and set B should occur in a single array. In JavaScript, a union set means adding one set element to the other set.

Example:

Javascript

function showUnion(sA, sB) {
    const union = new Set(sA);
    for (const num of sB) {
        union.add(num);
    }
    return union;
}
const s1 = new Set(['1', '6', '8']);
const s2 = new Set(['2', '3', '4']);
console.log(showUnion(s1, s2));

Output

Set(6) { '1', '6', '8', '2', '3', '4' }

Intersection of sets

An intersection of two sets means the element that occurs in both sets. In mathematical terms, the intersection of two sets is shown by A ∩ B. It means all the elements which is common in set A and set B should occur in a single array.

Example:

Javascript

function getIntersection(set1, set2) {
    const ans = new Set();
    for (let i of set2) {
        if (set1.has(i)) {
            ans.add(i);
        }
    }
    return ans;
}
const set1 = new Set([1, 2, 3, 8, 11]);
const set2 = new Set([1, 2, 5, 8]);

const result = getIntersection(set1, set2);
console.log(result);

Output

Set(3) { 1, 2, 8 }

Set difference

Set difference means that the array we subtract should contain all the unique element which is not present in the second array.

Example:

Javascript

let A = [7, 2, 6, 4, 5];
let B = [1, 6, 4, 9];
const set1 = new Set(A);
const set2 = new Set(B);

const difference = new Set();
set1.forEach(element => {
    if (!set2.has(element)) {
        difference.add(element);
    }
});
console.log([...difference]);

Output

[ 7, 2, 5 ]

Set Subset Operation

The set subset operation returns true if all the elements of setB are in setA.

Example:

Javascript

function subSet(val1, val2) {
    // Get an iterator for val2
    const iterator = val2.values();

    let nextVal = iterator.next();

    while (!nextVal.done) {
        if (!val1.has(nextVal.value)) {
            return false;
        }
        nextVal = iterator.next();
    }

    return true;
}

// Two sets
const val1 = new Set(['HTML', 'CSS', 'Javascript']);
const val2 = new Set(['HTML', 'CSS']);

const result = subSet(val1, val2);

console.log(result);

Output

true