Is it worth caching the length of an array in a Javascript loop? (v122)

Revision 122 of this benchmark created on

Description

http://stackoverflow.com/questions/5349425/whats-the-best-to-loop-an-array-in-javascript

Preparation HTML

<script>
  var myArray = new Array(100);
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
With caching
for (var i = 0, len = myArray.length; i < len; i++) {

}
ready
Without caching
for (var i = 0; i < myArray.length; i++) {

}
ready
Counting down
for (var i = myArray.length; i--;) {

}
ready
Caching length outside for loop
var len = myArray.length;

for (var i = 0; i < len; i++) {

}
ready
While loop
var len = myArray.length;
while (len--) {
  // blah blah
}
ready
Caching and incrementing inside for loop
for (var i = 0, len = myArray.length; i < len;) {
  i++;
}
ready
While loop counting up
var len = myArray.length;
var i = 0;
while (i < len) {
  i++;
}
ready
While loop counting up with !==
var len = myArray.length;
var i = 0;
while (i !== len) {
  i++;
}
ready
Not equal without cache
for (var i = 0; i !== myArray.length; i++) {

}
ready
Counting down full
for (var i = myArray.length; i >= 0; i--) {

}
ready
While loop counting down
var len = myArray.length;
while (len--) {

}
ready
Cahced, pre-increment
for (var i = 0, len = myArray.length; i < len; ++i) {

}
ready
Cahced outside, pre-increment
var len = myArray.length;

for (var i = 0; i < len; ++i) {

}
ready

Revisions

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