Global Variables vs Local Variables (v59)

Revision 59 of this benchmark created by Alessandro Cipolletti on

Description

This test compares the performance of global variables to local variables within functions.

Global variables should be slower because they do not exist in a function's activation object. JavaScript must traverse the Scope Chain to locate global variables.

Preparation HTML

<script>
    var a, b = 0;

    function x() {
        for (a = 0; a < 20; a++)
            b += a;
    }

    function w() {
        var c, d = 0;
        for (c = 0; c < 20; c++)
            d += c;
    }

    function y() {
        var c = a, d = b;
        for (c = 0; c < 20; c++)
            d += c;
    }

    function generate_z() {
       var e, f = 0;
       return function() {
        for (e = 0; e < 20; e++)
            f += e;
       }
    }

    z = generate_z();
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
Global variables
x();
ready
Local variables
w();
ready
Closure
z();
ready
Global to local variables
y();
ready

Revisions

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