The Set object type was introduced in ES6 (or ES2015), and along with the spread operator ..., you can use it to create a new array with only the unique values.
const array = [1, 1, 2, 3, 5, 5, 1] const uniqueArray = [...new Set(array)]]; console.log(uniqueArray); // Output is [1, 2, 3, 5]
Before ES6, isolating unique values would involve a lot more code than that.
This trick works for an array containing primitive types: undefined, null, boolean, string, and number. If you had an array containing objects, functions or additional arrays, or you'd need a different approach.