Getting unique values using sets in ES6.

unique.js

// with arrays
const dupArr = [1, 1, 2, 3, 1];
const uniArr = [...(new Set(dupArr))];
// [1, 2, 3]

// with objects on a key.
const dupObj = [{ id: 1, value: 'a' }, { id: 2, value: 'b' }, { id: 1, value: 'c' }];
const uniKeys = [...(new Set(dupObj.map(({ id }) => id)))];
// [ '1', '2' ]