Run results for: Loop Optimization

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko

Browser: IE 11

Operating system: Windows 7

Device Platform: Other

Date tested: 2025 years ago

Test name	Executions per second
For loop, basic	2038.8 Ops/sec
While loop, basic	1981.2 Ops/sec
For loop, cached (inside for statement)	3557.1 Ops/sec
For loop, cached (outside for statement)	3641.2 Ops/sec
For loop, i-- (caching inside for loop)	3530.7 Ops/sec
For loop, i-- (caching outside for loop)	3964.0 Ops/sec
While loop, cached	3784.6 Ops/sec
While loop, i--	3732.3 Ops/sec
forEach	2899.8 Ops/sec

Script Preparation code:

  var arr = [];
  for (var i = 0; i < 10000; i++) {
    arr.push(i);
  }

var sum = 0;

Tests:

For loop, basic
for (var i = 0; i < arr.length; i++) { sum += arr[i]; }
While loop, basic
var i = 0; while (i < arr.length) { sum += arr[i]; i++; }
For loop, cached (inside for statement)
for (var i = 0, len = arr.length; i < len; i++) { sum += arr[i]; }
For loop, cached (outside for statement)
var len = arr.length; for (var i = 0; i < len; i++) { sum += arr[i]; }
For loop, i-- (caching inside for loop)
for (var i = arr.length; i > 0; i--) { sum += arr[i]; }
For loop, i-- (caching outside for loop)
var i = arr.length; for (; i--;) { sum += arr[i]; }
While loop, cached
var len = arr.length; var i = 0; while(i < len){ sum += arr[i]; i++; }
While loop, i--
var i = arr.length; while(i--){ sum += arr[i]; }
forEach
arr.forEach(function(val){ sum += val; });