# JavaScript Program to Illustrate Different Set Operations

Last Updated : 18 Sep, 2023

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 âˆª 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 âˆ© 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
```