Run results for: For with and without external variables

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

Browser: Chrome 59

Operating system: Linux

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
1	419.6 Ops/sec
2	425.3 Ops/sec

Script Preparation code:

var arr = [];
for (var i = 0; i < 10000; i++) {
  arr.push({
    Number: i
  });
};

var e = null;
var f = null;

function doWork(o, i) {
  e = o;
};

​x
 
var arr = [];for (var i = 0; i < 10000; i++) {  arr.push({    Number: i  });};​var e = null;var f = null;​function doWork(o, i) {  e = o;};

Tests:

for (var i = 0, len = arr.length; i <= len; i++) {
  e = arr[i];
};

 
for (var i = 0, len = arr.length; i <= len; i++) {  e = arr[i];};

var i = 0;
var len = arr.length;

for (; i <= len; i++) {
  f = arr[i];
};

 
var i = 0;var len = arr.length;​for (; i <= len; i++) {  f = arr[i];};