how to chack for 5 duplicated items in array js code example
Example: duplicate numbers in an array javascript
[1, 1, 2, 2, 3].filter((element, index, array) => array.indexOf(element) !== index) // [1, 2][1, 1, 2, 2, 3].filter((element, index, array) => array.indexOf(element) !== index) // [1, 2]