javascript bubble sort
const bubbleSort = array => {
  const arr = Array.from(array); // avoid side effects
  for (let i = 1; i < arr.length; i++) {
    for (let j = 0; j < arr.length - i; j++) { // starts up to length - 1
      if (arr[j] > arr[j + 1]) {
        [arr[j], arr[j + 1]] = [arr[j + 1], arr[j]];
      }
    }
  }
  return arr;
};
console.log(bubbleSort([4, 9, 2, 1, 5]));
