caching length (v7)

Revision 7 of this benchmark created on

Preparation HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>

Setup

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

Test runner

Ready to run.

Testing in
TestOps/sec
cached
for (var i = 0, len = arr.length; i < len; i++) {
  arr[i] *= 2;
}
ready
not cached
for (var i = 0; i < arr.length; i++) {
  arr[i] *= 2;
}
ready
u wot m8
var len = 2;
len *= arr.length;
len -= len / 2;
for (var i = 0; i < len; i++) {
  arr[i] *= 2;
}
ready
while loop
var len = arr.length;
while (len--) {
  arr[len] *= 2;
}
ready
do-while loop
var len = arr.length;
do {
  arr[len] *= 2;
} while (len--);
ready
Prefix Increment
for (var i = 0; i < arr.length; ++i) {
  arr[i] *= 2;
}
ready
Prefix + Cached
for (var i = 0, len = arr.length; i < len; ++i) {
  arr[i] *= 2;
}
ready
Array map
arr.map(function(el) {
  return el * 2;
});
ready
iterator
function iterator(length, func) {
  for(var j = 0; j < length; j++) {
    func(j);
  }
}

iterator(arr.length, function(i) {
  arr[i] *= 2;
});
ready
forEach element
arr.forEach(function(element, index, array) {
  element *= 2;
});
ready
forEach index
arr.forEach(function(element, index, array) {
  array[index] *= 2;
});
ready
angularjs
angular.forEach(arr, function(value, key) {
  value*= 2;
});
ready
iterator2
function iterator(arr, func) {
  for(var j = 0; j < arr.length; j++) {
    func(j);
  }
}

iterator(arr, function(i) {
  arr[i] *= 2;
});
ready
iterator3
function iterator(arr, func) {
  for(var j = 0; j < arr.length; j++) {
    func(arr[j]);
  }
}

iterator(arr, function(item) {
  item *= 2;
});
ready
Sublime's "improved" for loop
for (var i = arr.length - 1; i >= 0; i--) {
  arr[i] *= 2;
}
ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.