Algorithms of sorting methods

mergeSort.js

function mergeSort(array) {
  if (array.length > 2) {
    let half = parseInt(array.length/2);
    let [left, rigth] = [mergeSort(array.slice(0, half)), mergeSort(array.slice(half))];
    let ret = [];
    for (let i = 0; i < array.length;i++) {
      if (left.length <= 0 || (rigth.length > 0 && left[0] > rigth[0]))
        ret.push(rigth.shift());
      else
        ret.push(left.shift());
    }
    return ret;
  }
  else if (array.length > 1 && array[0] > array[1])
    return [array[1], array[0]];
  else
    return array;
}

// mergeSort([1, 4, 2, 8, 345, 123, 43, 32, 5643, 63, 123, 43, 2, 55, 1, 234, 92])

quickSort.js

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

  let pivot = array[0],
    i = 0;
  for(let j = 0; j< array.length - 1; j++) {
    if(array[j+1] < pivot) {
      [array[j + 1], array[i+1]] = [array[i+1], array[j+1]];
      i++;
    }
  }
  [array[0], array[i]] = [array[i], array[0]];
  let firstPart = quickSort(array.slice(0,i));
  let secondPart = quickSort(array.slice(i + 1));
  firstPart.push(array[i]);
  return firstPart.concat(secondPart);
}

// quickSort([1, 4, 2, 8, 345, 123, 43, 32, 5643, 63, 123, 43, 2, 55, 1, 234, 92])