What is the difference between Set and a regular array? What is the complexity of the has() operation in Set?

A Set is a collection of unique values, unlike a regular array which can contain duplicates. Key differences:

• Uniqueness of elements: Set does not allow duplicate values.
• Fast lookup: the has() method checks for the presence of an element in constant time.
• No indices: Set does not support access by index like an array.

The complexity of the has() operation in a Set is O(1) on average, thanks to internal hashing or data structures that enable quick search. In contrast, checking for an element in an array (includes) is an O(n) operation, as it requires iterating over the elements.

Example:

const set = new Set([1, 2, 3]);
console.log(set.has(2)); // true

const arr = [1, 2, 3];
console.log(arr.includes(2)); // true