JSFiddle - React, Tailwind, and code Playground

by Sebastian Kay

JavaScript

function deleteNth(arr, n) {
  const resultMap = new Map();
  const resultList = [];

  for (num of arr) {
    const count = resultMap.has(num) ? resultMap.get(num) + 1 : 1;
    if (count <= n) {
      resultMap.set(num, count);
      resultList.push(num);
    }
  }

  return resultList;
}

const Test1 = deleteNth([20,37,20,21], 1); // [20,37,21]
const Test2 = deleteNth([1,1,3,3,7,2,2,2,2], 3); // [1, 1, 3, 3, 7, 2, 2, 2]

console.log(Test1  + " [20,37,21]");
console.log(Test2  + " [1, 1, 3, 3, 7, 2, 2, 2]");