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

Run details:

User agent: Mozilla/5.0 (Linux; Android 7.1.2; Meizu M8c Build/N2G47H) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.137 Mobile Safari/537.36

Browser: Chrome Mobile 64

Operating system: Android 7.1.2

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
Cache length	931.9 Ops/sec
Do not cache	453.1 Ops/sec

Script Preparation code:

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

AخA
 
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];
}

 
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];
}

 
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