Js Sets in JavaScript
? JavaScript Set
A Set is a built-in object that lets you store unique values of any type, whether primitive or objects.
What is a Set?
Stores unique values (no duplicates).
Can store any type: numbers, strings, objects, etc.
Useful when you want to keep track of distinct items.
Creating a Set
const mySet = new Set();const numbers = new Set([1, 2, 3, 4, 4]); console.log(numbers); // Set(4) {1, 2, 3, 4} — duplicates ignoredBasic Operations
| Operation | Example | Result |
|---|---|---|
| Add value | mySet.add(5); | Adds 5 to the set |
| Check existence | mySet.has(3); | Returns true if 3 exists |
| Delete value | mySet.delete(2); | Removes 2 if present |
| Get size | mySet.size; | Number of elements |
| Clear all | mySet.clear(); | Removes all elements |
Example Usage
const fruits = new Set();fruits.add("apple");fruits.add("banana");fruits.add("apple"); // ignored, duplicateconsole.log(fruits.has("banana")); // trueconsole.log(fruits.size); // 2fruits.delete("banana");console.log(fruits.has("banana")); // falseIterating Over a Set
const colors = new Set(["red", "green", "blue"]);for (const color of colors) { console.log(color);}Why Use Sets?
To remove duplicates from arrays easily:
const numbers = [1, 2, 2, 3, 4, 4];const uniqueNumbers = [...new Set(numbers)];console.log(uniqueNumbers); // [1, 2, 3, 4]If you want, I can explain WeakSet or Set methods in more detail!
