Answer 1

[3, 15, 8, 29, 102, 22] .sort((a,b) => a-b) // [3,8,15,22,29,102]
[3, 15, 8, 29, 102, 22] sort((a,b) => b-a) //[102, 29, 22, 15, 8, 3]

Answer 2

function reverse(num) {
  let numArr = num.toString().split("");
  return recuision(numArr);
}
function recuision(arr) {
  if (arr.length === 1) return arr.pop() + "";
  return arr.pop() + recuision(arr);
}
console.log(reverse(1234)); // "4321"
console.log(typeof reverse(1234)); // string