Tip: Get the unique values of an array in JavaScript.

ways-to-unique-arrays.js

// borrowed from Addy Osmani
// Way 1: new Set()
const uniqueArray = arr => [...new Set(arr)];

uniqueArray(['Dan', 'Sarah', 'Sophie‘， ’Sarah']);
// ["Dan", "Sarah", "Sophie"]

// Way 2: Array.from() and new Set()
const uniqueArray2 = arr => Array.from(new Set(arr));

// Way 3: using Array#filter and Set() - may be faster
const seen = new Set();
const uniqueArray3 = arr => arr.filter(x => {
  if (seen.has(x)) return false; seen.add(x);
  return true;
});