Closed. This question needs debugging details. It is not currently accepting answers. Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question. Closed last month. This post was edited and submitted for review 1 hour ago. Improve this question I have an array with duplicate numbers in it. I need to find the duplicate value and increment the duplicate value and so on. Input : array = [1,2,3,4,4,5,6,7,8,8,9,10]; Expected Result: array = [1,2,3,4,5,6,7,8,9,10,11,12] const array = [1,2,3,4,4,5,6,7,8,8,9,10]; const duplicates = array.filter((item, index) => array.indexOf(item) !== index); console.log(duplicates); // Output: [2, 4, 5]