What is a unique value in an array?
// usage example:
var myArray = ['a', 1, 'a', 2, '1'];
var unique = myArray.filter((v, i, a) => a.indexOf(v) === i);
// unique is ['a', 1, 2, '1']
const myArray = [1,2,3,1,5,8,1,2,9,4];
const unique = [...new Set(myArray)]; // [1, 2, 3, 5, 8, 9, 4]
const myString = ["a","b","c","a","d","b"];
const uniqueString = [...new Set(myString)]; //["a", "b", "c", "d"]
The unique values are the only ones that can be put in the array. So if you have an array of numbers, a unique value could be anyone from 1 to 100, except 99.