filter unique elements in array javascript code example

Example 1: javascript array unique values

var arr = [55, 44, 65,1,2,3,3,34,5];
var unique = [...new Set(arr)]

//just  var unique = new Set(arr) wont be an array

Example 2: array unique values javascript

const myArray = ['a', 1, 'a', 2, '1'];
const unique = [...new Set(myArray)]; // ['a', 1, 2, '1']

Example 3: find unique elements in array javascript

let a = ["1", "1", "2", "3", "3", "1"];
let unique = a.filter((item, i, ar) => ar.indexOf(item) === i);
console.log(unique);

Example 4: javascript remove uniques from array

function getNotUnique(array) {
    var map = new Map();
    array.forEach(a => map.set(a, (map.get(a) || 0) + 1));
    return array.filter(a => map.get(a) > 1);
}

console.log(getNotUnique([1, 2, 2, 4, 4])); //[2, 2, 4, 4]
console.log(getNotUnique([1, 2, 3] )); //[]