Bubble sort and merge sort

index.js

// run with `node index.js`

function bubbleSort(list) {
  for (let limit = 1; limit < list.length; limit++) {
    for (let i = 0; i < list.length - limit; i++) {
      let left = list[i];
      let right = list[i + 1];
      if (left > right) {
        list[i] = right;
        list[i+1] = left;
      }
    }
  }
  return list;
}

function merge(left, right) {
  let lpos = 0;
  let rpos = 0;
  let result = [];
  for (let i = 0; i < (left.length + right.length); i++) {
    if (lpos === left.length) {
      result.push(right[rpos]);
      rpos = rpos + 1;
    } else if (rpos === right.length) {
      result.push(left[lpos]);
      lpos = lpos + 1;
    } else if (left[lpos] < right[rpos]) {
      result.push(left[lpos]);
      lpos = lpos + 1;
    } else {
      result.push(right[rpos]);
      rpos = rpos + 1;
    }
  }
  return result;
}

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

  // divide in two
  let left = list.slice(0, list.length / 2);
  let right = list.slice(list.length / 2, list.length);

  // sort each half
  let sorted_left = mergeSort(left);
  let sorted_right = mergeSort(right);

  // merge
  return merge(sorted_left, sorted_right);
}


function sortTimed(sortFun, list) {
  // Start timing
  const startTime = process.hrtime();
  let sorted = sortFun(list);
  const endTime = process.hrtime(startTime);
  const elapsedNanoseconds = endTime[1];
  return  elapsedNanoseconds
}

function main() {
  var list = [];
  for (var i = 0; i <= 100000; i++) {
    list.push(i);
  }

  let time = sortTimed(bubbleSort, list);
  console.log(`Bubble sort: ${time}ns`);

  let time2 = sortTimed(mergeSort, list);
  console.log(`Merge sort:  ${time2}ns`);

  console.log(`Proportion: ${Math.ceil(100 * time / time2)}% slower`);
}


main()