for vs forEach

JavaScript performance comparison

Revision 162 of this test case created by Joey Schooley

Info

Is it faster to use the native forEach or just loop with for?

Takes into account the variables / functions required by each method.

Preparation code

<script>
  var values = [];
  var sum = 0;
  for (var i = 0; i < 10000; i++) {
   values[i] = i;
  }
</script>

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
forEach
values.forEach(function (val) {
   sum += val;
});
pending…
for loop, uncached length
for (var j = 0; j < values.length; j++) {
 sum += values[j];
}
pending…
for loop, cached length
for (var j = 0, l = values.length; j < l; j++) {
 sum += values[j];
}
pending…
for loop, reverse, cached length, iteration statement
for (var l = values.length - 1; l >= 0; l--) {
 sum += values[l];
}
pending…
for loop, reverse, cached length, no iteration statementmal reverse
for (var l = values.length; l--;) {
 sum += values[l];
}
pending…
for in
for (var j in values) {
 sum += values[j];
}
pending…
while loop, cached length
var l = values.length;
while (l--) {
 sum += values[l];
}
pending…
while loop, cached length, no code block
var l = values.length;
while (l-- && (sum += values[l]));
pending…
for loop, cached length, no code block (minimalist)
for (var l = values.length; l-- && (sum += values[l]););
pending…

Compare results of other browsers

Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

0 comments

Add a comment