Codewars - Delete occurrences of an element if it occurs more than n times

#learning #javascript #programming #beginners

Salutations.

I'm posting Codewars challenges and my thought process in this series. I'm using JS and Node 18 whenever possible. Just for the sake of clarity, I'm making fair use of them.

"Delete occurrences of an element if it occurs more than n times". In essence, trim parts in the middle of the array, without altering the order.

function deleteNth(arr,n){
  let counter = {"top": n , "undef": 0};

  for (let i = 0 ; i < arr.length ; i++ ){
    (counter[arr[i]]) ? null : counter[arr[i]] = 0;
    if (counter[arr[i]] < n){
      counter[arr[i]]++;
    } 
    else {
      arr[i] = undefined;
      counter.undef++;
    }
  }

  arr.sort((a,b) => 0);

  for (let i = 0 ; i < counter.undef ; i++){
    arr.pop();
  }

  return arr;
}