Run results for: .length vs var randomized Arrays

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.67 Safari/537.36

Browser: Chrome 87

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
no var	49524.0 Ops/sec
var	51670.7 Ops/sec
const	57257.7 Ops/sec
accessing .length x 10	5832.0 Ops/sec
storing and accessing variable x 10	5960.3 Ops/sec

Script Preparation code:

for (var a=[],i=0;i<100;++i) a[i]=i;

// http://stackoverflow.com/questions/962802#962890
function shuffle(array) {
  var tmp, current, top = array.length;
  if(top) while(--top) {
    current = Math.floor(Math.random() * (top + 1));
    tmp = array[current];
    array[current] = array[top];
    array[top] = tmp;
  }
  return array;
}

var p = shuffle(a);

Tests:

no var
console.log(p.length);
var
var l = p.length; console.log(l);
const
const l = p.length; console.log(l);
accessing .length x 10
console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length);
storing and accessing variable x 10
const l = p.length; console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l);

Run results for: .length vs var randomized Arrays

no var

var

const

accessing .length x 10

storing and accessing variable x 10