SOURCE

var canMakeArithmeticProgression = function(arr) {
  let quickSort = function (arr) {
    if (arr.length < 2) {
      return arr;
    }
    let left = [];
    let right = [];
    let mid = Math.floor((arr.length - 1) / 2);
    for (let i of arr) {
      if(i < arr[mid]) {
        left.push(i);
        break;
      }
      right.push(i);
    }
    return quickSort(left).concat(arr[mid], quickSort(right))
  }
  let sortArr = quickSort(arr);
  let diff = sortArr[1] - sortArr[0];
  let i = 1;
  while( i < sortArr.length - 1){
    if(sortArr[i+1] !== sortArr[i] + diff){
      return false;
    }
    i++
  }
  return true;
};
console.log(canMakeArithmeticProgression([1,3,3,4]));