Is it worth caching the length of an array in a Javascript loop? (v68)

Revision 68 of this benchmark created on


Description

Preparation HTML

<script>
  var myArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20];
</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
len = myArray.length;

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

}
ready
while loop
len = myArray.length;
while (len--) {
 // blah blah
}
ready
for check index
for (var i = 0; myArray[i++];) {

}
ready
Counting down without coercion
for (var i = myArray.length; -1 < --i;) {

}
ready
Counting down without coercion
for (var i = myArray.length; --i > -1;) {

}
ready

Revisions

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