JavaScript Performance Benchmarking

jsperfbenchamrk.js

//Perf benchmarking for array sorting.
//Run these lines in the browser console

//1. Bubble Sort
var t1 = performance.now();
var arr = [29, 30, 100, 300, 400, 12, 1, 45, 67, 29, 30, 100, 300, 400, 12, 1, 45, 67, 29, 30, 100, 300, 400, 12, 1, 45, 67];

for(var i=0;i<arr.length;i++) {
	for(var j=0; j<arr.length-i-1;j++) {
		if(arr[j] > arr[j+1]) {
			var temp = arr[i];
			arr[i] = arr[j];
			arr[j] = temp;
		}
	}
}
//console.log(arr);
var t2 = performance.now();
console.log('time taken: ' + (t2 - t1));

--------------------------------------------
//2. Native JS sort()
var t1 = performance.now();
var arr = [29, 30, 100, 300, 400, 12, 1, 45, 67, 29, 30, 100, 300, 400, 12, 1, 45, 67, 29, 30, 100, 300, 400, 12, 1, 45, 67];

arr = arr.sort(function(a,b) {
	return a - b;
});
//console.log(arr);
var t2 = performance.now();
console.log('time taken: ' + (t2 - t1));

---------------------------------------------
//3. Merge Sort
function mergeSort (arr) {
  if (arr.length === 1) {
    // return once we hit an array with a single item
    return arr
  }

  const middle = Math.floor(arr.length / 2) 
  const left = arr.slice(0, middle) 
  const right = arr.slice(middle)

  return merge(
    mergeSort(left),
    mergeSort(right)
  )
}
function merge (left, right) {
  let result = []
  let indexLeft = 0
  let indexRight = 0

  while (indexLeft < left.length && indexRight < right.length) {
    if (left[indexLeft] < right[indexRight]) {
      result.push(left[indexLeft])
      indexLeft++
    } else {
      result.push(right[indexRight])
      indexRight++
    }
  }
  return result.concat(left.slice(indexLeft)).concat(right.slice(indexRight))
}

var t1 = performance.now();
var arr = [29, 30, 100, 300, 400, 12, 1, 45, 67, 29, 30, 100, 300, 400, 12, 1, 45, 67, 29, 30, 100, 300, 400, 12, 1, 45, 67];

arr = mergeSort(arr);

var t2 = performance.now();
console.log('time taken: ' + (t2 - t1));

//Output: Merge Sort is fastest > Native sort() > Bubble Sort
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