Run results for: Caching length property vs getting it each time in the loop

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/127.0.6533.107 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 127

Operating system: iOS 17.6

Device Platform: Mobile

Date tested: one year ago

Cache length

48K/s

Do not cache

23K/s

View exact numbers

Test name	Executions per second
✓ Cache length	47,864 Ops/sec
Do not cache	23,375 Ops/sec

Script Preparation code:

var arr = [];
var count = 1000;
for(var i = 0; i<count; i++)
{
  arr.push(i);
}

Tests:

Cache length
var arrLen = arr.length; var sum = 0; for (var i = 0; i < arrLen; i++){ sum = arr[i]; }
Do not cache
var sum = 0; for (var i = 0; i < arr.length; i++){ sum = arr[i]; }

Run results for: Caching length property vs getting it each time in the loop

save length of the array in the variable vs get it the loop

Cache length

Do not cache