JavaScript Set and Map

Set: Unique Values

Set stores unique values. No duplicates allowed.

const numbers = new Set([1, 2, 3, 3, 4]);
console.log(numbers); // Set {1, 2, 3, 4}

numbers.add(5);
numbers.has(3); // true
numbers.delete(2);

Use when: You need unique values

Map: Key-Value Pairs

Map is like object but with any key type.

const map = new Map();
map.set('name', 'John');
map.set(1, 'One');
map.set(true, 'Yes');

map.get('name'); // "John"
map.has('name'); // true

Use when: You need keys that aren't strings

Key Takeaway

Set stores unique values. Map stores key-value pairs with any key type. Use when arrays/objects aren't enough.