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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:131.0) Gecko/20100101 Firefox/131.0

Browser: Firefox 131

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Do not cache

1.9M/s

Cache length

1.9M/s

View exact numbers

Test name	Executions per second
✓ Do not cache	1,909,097 Ops/sec
Cache length	1,906,313 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]; }