(fixed) for vs forEach vs while

JavaScript performance comparison

Revision 115 of this test case created

Info

Is it faster to use the native forEach or just loop with for? And how fast is while?

Preparation code

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

  function add(val) {
    sum += val;
  }
</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(add);
pending…
for loop, simple
for (i = 0; i < values.length; i++) {
  add(values[i]);
}
pending…
for loop, cached length
var len = values.length;
for (i = 0; i < len; i++) {
  add(values[i]);
}
pending…
for loop, reverse
for (i = values.length - 1; i >= 0; i--) {
  add(values[i]);
}
pending…
forEach more local
(function() {
  var sum = 0;
  values.forEach(function(val) {
    sum += val;
  });
})();
pending…
for..int
for (var i in values) {
  add(values[i]);
}
pending…
cached, in for
for (var i = 0, len = values.length; i < len; i++) {
  add(values[i]);
}
pending…
while
i=0;
len=values.length
while (i++<len) {
  add(values[i]);
}
pending…
while ++i
i=-1;
len=values.length;
while (++i<len) {
  add(values[i]);
}
pending…
for cached with ++i
for (var i = 0, len = values.length; i < len, item = values[i]; ++i) {
  add(item);
}
 
pending…
asdf
for (var i = 0, len = values.length; i < len;  ++i) {
item = values[i];
  add(item);
}
 
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