for vs forEach (v218)

Revision 218 of this benchmark created on

Description

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

Inspired by Adrian Sutton's tests at: http://www.symphonious.net/2010/10/09/javascript-performance-for-vs-foreach/

This one adds random floating point numbers to see if the loop overhead is significant at all in the face of standard work.

Preparation HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>

Setup

var i,
        value,
        length,
        values = [],
        sum = 0,
        context = values;
    
    
    for (i = 0; i < 10000; i++) {
        values[i] = Math.random();
    }
    
    function add(val) {
        sum += val;
    }

Teardown


    i = 0;
    value = 0;
    length = 0;
    values = [];
    sum = 0;

Test runner

Ready to run.

Testing in
TestOps/sec
forEach
values.forEach(add);
ready
for loop, simple
for (i = 0; i < values.length; i++) {
    sum += values[i];
}
ready
for loop, cached length
length = values.length;
for (i = 0; i < length; i++) {
    sum += values[i];
}
ready
for loop, cached length
length = values.length;
for (i = 0; i < length; i++) {
    sum += values[i];
}
ready
for loop, cached length, callback
var length = values.length;
for (var i = 0; i < length; i++) {
    add(values[i], i, values);
}
ready
for loop, length cached inside
for (i=0, len = values.length; i<len; i++) {
   sum += values[i];
}
ready
for loop, length cached inside
for (i=0, len = values.length; i<len; i++) {
   sum += values[i];
}
ready
for loop, length cached inside
for (i=0, len = values.length; i<len; i++) {
   sum += values[i];
}
ready

Revisions

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