Run results for: For loop inline array.length vs captured variable

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:49.0) Gecko/20100101 Firefox/49.0

Browser: Firefox 49

Operating system: Windows

Device Platform: Other

Date tested: 7 years ago

Script Preparation code:

var a = [];
for (var i = 0; i < 10000; i++) {
  a.push(Math.random());
}

function getLength() {
  return a.length;
}

Tests:

Inline
for (var i = 0; i < a.length; i++) { a[i] = a[i] * Math.random(); }
Captured
for (var i = 0, ilen = a.length; i < ilen; i++) { a[i] = a[i] * Math.random(); }
Getter function
for (var i = 0; i < getLength(); i++) { a[i] = a[i] * Math.random(); }
Map
a = a.map(v => v * Math.random());