Run results for: Compare the cost of Array.prototype.length

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36

Browser: Chrome 76

Operating system: Mac OS X 10.14.5

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Using Array.prototype length all the time	6197.4 Ops/sec
Caching the value of Array.prototype.length	12532.6 Ops/sec

Script Preparation code:

var array = [];
for(var i = 0; i < 1000; i++){
  array[i] = i;
}

Tests:

Using Array.prototype length all the time
var sum = 0; for (var i = 0; i < array.length; i++) { sum += array[i]; }
Caching the value of Array.prototype.length
var sum = 0; var len = array.length; for (var i = 0; i < len; i++) { sum += array[i]; }