for vs forEach (v36)

Revision 36 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/

Adds random numbers rather than sequentially increasing numbers to avoid any numerical bias that might occur from adding increasing or decreasing numbers in forward or reverse.

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.floor(Math.random() * 100);
    }
    
    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, reverse
for (i = values.length - 1; i >= 0; i--) {
    sum += values[i];
}
ready
for loop, cached length, callback
length = values.length;
for (i = 0; i < length; i++) {
    add(values[i], i, values);
}
ready
for loop, cached length, callback.call
length = values.length;
for (i = 0; i < length; i++) {
    add.call(context, values[i], i, values);
}
ready
$.each
$.each(values, function(key, value) {
    sum += value;
});
ready
for ... in
for (i in values) {
    sum += values[i];
}
ready
for loop, reverse, decrement condition
for (i = values.length; i--;) {
    sum += values[i];
}
ready
for loop, reverse, pre-decrement
for (i = values.length - 1; i >= 0; --i) {
    sum += values[i];
}
ready
for loop, assignment condition
for (i = 0; (value = values[i]) !== undefined; i++) {
    sum += value;
}
ready
for loop, assignment condition, reversed
for (i = values.length - 1; (value = values[i]) !== undefined; i--) {
    sum += value;
}
ready
for loop, assignment condition, callback
for (i = 0; (value = values[i]) !== undefined; i++) {
    add(value, i, values);
}
ready
for loop, assignment condition, callback.call
for (i = 0; (value = values[i]) !== undefined; i++) {
    add.call(context, value, i, values);
}
ready

Revisions

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