how to filter unique element in javascript code example
Example 1: javascript find unique values in 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']
Example 2: 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] )); //[]