Loops (long array) (more accurate tests) (v10)

Revision 10 of this benchmark created by Thomas Aylott on

Description

Creates the array with actual values and uses the result in an expression to keep the browser from optimizing in weird ways or something maybe.

Preparation HTML

<script>
  var arr = [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3];
  
  var something = 0
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
while loop that imitates a for loop
var i = 0;
while (i < arr.length) {
 something + arr[i];
 i++;
};
ready
while loop that imitates a for loop, caching the length
var i = 0,
    len = arr.length;
while (i < len) {
 something + arr[i];
 i++;
};
ready
Reverse while loop
var i = arr.length;
while (i--) {
 something + arr[i];
};
ready
Reverse do … while loop
var i = arr.length;
do {
 something + arr[i];
} while (i--);
ready
Reverse for loop
for (var i = arr.length; i--;) {
 something + arr[i];
};
ready
Old ’n’ busted for loop
for (var i = 0; i < arr.length; ++i) {
 something + arr[i];
};
ready
Old ’n’ busted for loop, caching the length
for (var i = 0, len = arr.length; i < len; ++i) {
 something + arr[i];
};
ready
Cool guy loop
for (var i = -1; ++i < arr.length;) {
 something + arr[i];
};
ready
Cool guy loop, caching the length
for (var i = -1, len = arr.length; ++i < len;) {
 something + arr[i];
};
ready
Native Array#forEach implementation
arr.forEach(function(x) {
 something + x;
});
ready
Native Array#forEach implementation with named function
function foo(x) {
 something + x;
};
arr.forEach(foo);
ready
Unrolled loop
for (var i = 0, len = arr.length; i < len; i = i + 10) {
 something + arr[i];
 something + arr[i + 1];
 something + arr[i + 2];
 something + arr[i + 3];
 something + arr[i + 4];
 something + arr[i + 5];
 something + arr[i + 6];
 something + arr[i + 7];
 something + arr[i + 8];
 something + arr[i + 9];
};
ready
Native Array#forEach with cached function
// This one is faster because it only creates the function on its first run
// So the more iterations it runs, the faster it'll be relative to the other tests
if (!window.forEachMe) window.forEachMe = function(x) {
 something + x
}

arr.forEach(forEachMe);
ready

Revisions

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