Flattening an 'n-level' nested array in javascript

Input: const input = [1, 2, [3, 4], 5, [[[6, 7], 8, [[[[9]]]]]], 10, 11, [12]] Expected Output: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] What's flattening of arrays in javascript? Flattening an array in JavaScript refers to the process of transformi...