Run results for: for loop array caching with mutations

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.67 Safari/537.36

Browser: Chrome 87

Operating system: Mac OS X 10.14.6

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
mutate without length caching	187.5 Ops/sec
mutate with length caching	185.2 Ops/sec
separate array without length caching	244.8 Ops/sec
separate array with length caching	135.9 Ops/sec

Script Preparation code:

var arr = Array.from({length: 10000}, (_, i) => String.fromCharCode(i + 97));

Tests:

mutate without length caching
for (let i = 0; i < arr.length; i++) { arr[i] = "(" + arr[i] + ")"; }
mutate with length caching
for (let i = 0, l = arr.length; i < l; i++) { arr[i] = "(" + arr[i] + ")"; }
separate array without length caching
const arr1 = []; for (let i = 0; i < arr.length; i++) { arr1[i] = "(" + arr[i] + ")"; } arr = arr1;
separate array with length caching
const arr1 = []; for (let i = 0, l = arr.length; i < l; i++) { arr1[i] = "(" + arr[i] + ")"; } arr = arr1;