There are multiple ways how to remove a duplicate value from a JavaScript array using indexOf() and filter(), and forEach() and include() methods. Yet using Set with a combination of spread operator is the simplest approach.

A Set is an iterable object which lets you store unique values of any type, whether primitive values or object references. We use the spread syntax (...) to convert the Set object to an array.

Copycopy code to clipboard
1const arr = [1, 2, 3, 5, 3, 8, 13, 13, 21, 5, 3, 2, 21];
2
3console.log([...new Set(arr)]);
4// Output: [1, 2, 3, 5, 8, 13, 21]