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 18_6_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.6 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 18

Operating system: iOS 18.6.2

Device Platform: Mobile

Date tested: 8 months ago

Do not cache

3.2M/s

Cache length

3.2M/s

View exact numbers

Test name	Executions per second
✓ Do not cache	3,226,688 Ops/sec
Cache length	3,212,033 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]; }