Run results for: for vs forEach vs map : array creation : 2019

This test is to test the return of an array from these loops. A lot of the test are incorrect because .map returns an array. So it will only be fair to test the speeds based on returning a new array from all loops.

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36

Browser: Chrome 78

Operating system: Mac OS X 10.15.1

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
for - create new array	5484.1 Ops/sec
forEach - create new array	6951.1 Ops/sec
map - create new array	8366.6 Ops/sec
for - overwrite array	4400.2 Ops/sec
forEach - overwrite array	5791.8 Ops/sec
map - overwrite array	7969.6 Ops/sec

Script Preparation code:

   var arr = [];

	function resetArray(){
      for (var i = 0; i < 1000; i++) {
        arr[i] = i;
      }
    }
  
    function someFn(i) {
      return i * 3 * 8;
    }

	resetArray()

Tests:

for - create new array
resetArray() var forArray = [] var length = arr.length for (var i = 0; i < length; i++) { forArray.push(someFn(arr[i])); }
forEach - create new array
resetArray() var forEachArray = [] arr.forEach(function (item, index){ forEachArray.push(someFn(item)); })
map - create new array
resetArray() var mapNewArray = []; mapNewArray = arr.map(function(item){ return someFn(item) })
for - overwrite array
resetArray() var len = arr.length for (var i = 0; i < len; i++) { arr[i] = someFn(arr[i]); }
forEach - overwrite array
resetArray() arr.forEach(function (item, index){ arr[index] = someFn(item); })
map - overwrite array
resetArray() arr = arr.map(function(item, index){ return someFn(item) })

Run results for: for vs forEach vs map : array creation : 2019

This test is to test the return of an array from these loops. A lot of the test are incorrect because .map returns an array. So it will only be fair to test the speeds based on returning a new array from all loops.

for - create new array

forEach - create new array

map - create new array

for - overwrite array

forEach - overwrite array

map - overwrite array