How do you convert a Set to an Array?

The short answer

The two main ways are the spread operator ([...set]) and Array.from(set). Both produce a regular array from a Set. This is commonly used to remove duplicates from an array.

The methods

1const mySet = new Set([1, 2, 3, 4, 5]);
2
3// Spread operator (most common)
4const arr1 = [...mySet]; // [1, 2, 3, 4, 5]
5
6// Array.from
7const arr2 = Array.from(mySet); // [1, 2, 3, 4, 5]

Removing duplicates from an array

This is the most practical use case:

1const numbers = [1, 2, 2, 3, 3, 3, 4];
2const unique = [...new Set(numbers)]; // [1, 2, 3, 4]

One line — create a Set (which automatically removes duplicates), then spread it back into an array.

For objects, you need a different approach since Sets use reference equality:

1const users = [
2  { id: 1, name: 'John' },
3  { id: 2, name: 'Jane' },
4  { id: 1, name: 'John' },
5];
6
7// Remove duplicates by id
8const unique = [
9  ...new Map(users.map((u) => [u.id, u])).values(),
10];

Why interviewers ask this

This tests knowledge of Sets and array conversion. The duplicate removal pattern is something you use in real code, and knowing it shows practical JavaScript skills.