sort.js

function sort(list) {
  if (list.length == 1) {
    return list;
  }
  var listA = sort(list.slice(0, list.length / 2))
  var listB = sort(list.slice(list.length / 2))
  var indexA = 0
  var indexB = 0
  var newList = []
  while (indexA < listA.length || indexB < listB.length) {
    if (indexA !== listA.length && (listA[indexA] < listB[indexB] || indexB === listB.length)) {
      newList.push(listA[indexA]);
      indexA++
    } else {
      newList.push(listB[indexB]);
      indexB++
    }
  }
  return newList;
}

var list = []
for (var i = 0; i < 1000; i++) {
  let random = Math.floor(Math.random() * 1000)
  if(!list.includes(random)){
    list.push(random)
  }
}
console.log(sort(list));