如何在保持顺序的同时对数组进行排序

function mergeSort(arr) {
  if (arr.length <= 1) {
    return arr;
  }
  
  const mid = Math.floor(arr.length / 2);
  const left = arr.slice(0, mid);
  const right = arr.slice(mid);
  
  return merge(mergeSort(left), mergeSort(right));
}

function merge(left, right) {
  let result = [];
  let i = 0;
  let j = 0;
  
  while (i < left.length && j < right.length) {
    if (left[i] <= right[j]) {
      result.push(left[i]);
      i++;
    } else {
      result.push(right[j]);
      j++;
    }
  }
  
  while (i < left.length) {
    result.push(left[i]);
    i++;
  }
  
  while (j < right.length) {
    result.push(right[j]);
    j++;
  }
  
  return result;
}

const arr = [4, 2, 7, 1, 5];
const sortedArr = mergeSort(arr);
console.log(sortedArr);