Different kinds of loop (v3)

Revision 3 of this benchmark created on

Description

In this revision I've updated the tests to call a function rather than count++; which is then not used.

I did this as in theory it's possible that some browsers will be able to see this variable is unused and optimise out that code so it's never run.

A real world app is unlikely to contain unused code, so this could skew the tests. - Jamie Mason / @GotNoSugarBaby

Preparation HTML

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script>
  var arr = [], obj = {};
  
  (function ()
  {
      for( var i = 0; i < 1000; i++ ) {
          arr[i] = 'value' + i;
          obj[i] = 'value' + i;
      }    
  }());
  
  function someFn (ix)
  {
      return ix * 5 + 1 / 3 * 8;
  }
  
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
arr.forEach
if ('forEach' in arr)
{
    arr.forEach(function(value, i, arr) {
        someFn(i);
    });
}
else {
    // i'm not testing shims
    for( var i = 0; i < arr.length; i++ ) {
        someFn(i);
    }
}
ready
var i in arr
for( var i in arr ) {
    someFn(i);
}
ready
var i in arr (with hasOwnProperty check)
for( var i in arr ) {
    if( !arr.hasOwnProperty( i ) ) continue;
    someFn(i);
}
ready
var i in obj
for( var i in obj ) {
    someFn(i);
}
ready
var i in obj (with hasOwnProperty check)
for( var i in obj ) {
    if( !obj.hasOwnProperty( i ) ) continue;
    someFn(i);
}
ready
for i < arr.length (without caching)
for( var i = 0; i < arr.length; i++ ) {
    someFn(i);
}
ready
for i < arr.length (with caching)
for( var i = 0, max = arr.length; i < max; i++ ) {
    someFn(i);
}
ready
for, counting down
for (var i = arr.length; i > 0; i--) {
    someFn(i);
}
ready
while i < arr.length (without caching)
var i = 0;
do 
{
    someFn(i);
    i++;
}
while (i < arr.length);
ready
while i < arr.length (with caching)
var i = 0, max = arr.length;
do 
{
    someFn(i);
    i++;
}
while (i < max);
ready
while, counting down
var i = arr.length;
do
{
    someFn(i);
    i--;
}
while (i > 0);
ready
while, counting down (2)
var i = arr.length - 1;
do
{
    someFn(i);
}
while (i--);
ready
while, counting down (3)
var i = arr.length;
if (i > 0)
{
    do
    {
        someFn(i);
    }
    while (--i); // i must be greater than 0 here
}
ready
$.each
$.each(arr, function(key, val) {
  someFn(key);
});
ready

Revisions

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