JavaScript Sets and Maps: Beyond Arrays and Objects

How to handle unique values and key-value pairs properly without type coercion and performance issues

Sets and Maps are specialized data structures in JavaScript, each designed to solve specific problems that arrays and objects handle poorly.

A Set is a collection of unique values. Think of it like a bag that automatically removes duplicates.

When you add the same value twice, the Set keeps only one copy. It’s perfect for maintaining lists where each item should appear only once.

A Map is a collection of key-value pairs where keys can be any type - numbers, strings, objects, even functions. Unlike objects, which convert all keys to strings, Maps preserve the type of the key. This makes them ideal for creating dictionaries or caches where the key type matters.