🔥 JavaScript Set Logic Just Leveled Up (2025 Update)

The JavaScript Set object just became a powerhouse of logic operations. With 7 new methods added in 2025, writing readable and efficient set-based logic is now a breeze! 🎯

Let's break it down 👇

📦 What’s New in Set Logic?

JavaScript 2025 introduced 7 logical methods to the Set prototype:

union()
difference()
intersection()
symmetricDifference()
isSubsetOf()
isSupersetOf()
isDisjointFrom()

✅ Supported since mid-2024 in all modern browsers:
Chrome 122, Edge 122, Firefox 127, Safari 17, Opera 108

🔗 1. union()

Combines all unique values from two sets.

const A = new Set(['a', 'b', 'c']);
const B = new Set(['b', 'c', 'd']);
const C = A.union(B);

console.log(C); // Set(4) { 'a', 'b', 'c', 'd' }

🤝 2. intersection()

Returns elements common to both sets.

const A = new Set(['a', 'b', 'c']);
const B = new Set(['b', 'c', 'd']);
const C = A.intersection(B);

console.log(C); // Set(2) { 'b', 'c' }

➖ 3. difference()

Returns elements in the first set that aren’t in the second.

const A = new Set(['a', 'b', 'c']);
const B = new Set(['b', 'c', 'd']);
const C = A.difference(B);

console.log(C); // Set(1) { 'a' }

🔁 4. symmetricDifference()

Returns elements that are in either set but not both.

const A = new Set(['a', 'b', 'c']);
const B = new Set(['b', 'c', 'd']);
const C = A.symmetricDifference(B);

console.log(C); // Set(2) { 'a', 'd' }

🧩 5. isSubsetOf()

Checks if all elements in A exist in B.

const A = new Set(['b', 'c']);
const B = new Set(['a', 'b', 'c', 'd']);
console.log(A.isSubsetOf(B)); // true

📚 6. isSupersetOf()

Checks if A contains all elements of B.

const A = new Set(['a', 'b', 'c', 'd']);
const B = new Set(['b', 'c']);
console.log(A.isSupersetOf(B)); // true

🚫 7. isDisjointFrom()

Checks if A and B share no common elements.

const A = new Set(['x', 'y']);
const B = new Set(['a', 'b']);
console.log(A.isDisjointFrom(B)); // true

📘 Why This Matters

Previously, you'd write verbose loops or use helper libraries like Lodash for set logic. Now, JavaScript handles it natively — cleaner, faster, and more readable.

🧠 Final Thoughts

The new Set methods finally give us the expressive power we’ve needed in native JavaScript. Whether you're working with data structures, filtering sets, or building graph logic — this update is a total game-changer.

💬 What will you use these for? Drop your thoughts in the comments!

🔗 Full Reference

For all things Set, check out: JavaScript Set Reference on MDN