bubble, selection, merge, and quick sorts

sorting.js

function bubbleSort(arr) {
  for (let outer = 0; outer < arr.length; outer++) {
    for (let i = 0; i < arr.length - 1 - outer; i++) {
      if (arr[i] > arr[i + 1]) {
        [arr[i], arr[i + 1]] = [arr[i + 1], arr[i]];
      }
    }
  }

  return arr;
}

function selectionSort(arr) {
  for (let outer = 0; outer < arr.length; outer++) {
    let min = arr[outer], pos = outer;
    for (let i = outer + 1; i < arr.length; i++) {
      if (arr[i] < min) {
        min = arr[i];
        pos = i;
      }
    }

    [arr[outer], arr[pos]] = [arr[pos], arr[outer]];
  }

  return arr;
}

function mergeSort(arr) {
  if (arr.length === 1) {
    return arr;
  }

  const mid = Math.floor(arr.length / 2);
  return merge(mergeSort(arr.slice(0, mid)), mergeSort(arr.slice(mid)));
}

function merge(left, right) {
  const arr = [];
  while (left.length || right.length) {
    if (!right.length || (left.length && left[0] < right[0])) {
      arr.push(left.shift());
    } else {
      arr.push(right.shift());
    }
  }
  return arr;
}

function quickSort(arr) {
  if (arr.length <= 1) {
    return arr;
  }

  const referencePoint = arr[0];
  const left = [];
  const right = [];

  for (let i = 1; i < arr.length; i++) {
    let item = arr[i];
    if (item < referencePoint) {
      left.push(item);
    } else {
      right.push(item);
    }
  }
  return [...quickSort(left), referencePoint, ...quickSort(right)];
}

module.exports = { bubbleSort, selectionSort, mergeSort, quickSort };