Global Variables vs Local Variables (v22)

Revision 22 of this benchmark created 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>
  function b () {
}

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

var d = function () {
}

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

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

window.v = function () {
}

  function z(){
    for(var a=0;a<20;a++)
       window.v();
  }

  var d =   function (w) { return function () {
    for(var a=0;a<20;a++)
       w.v();
  };}(window)

window.o = { a: function(){} };

  var p = function () {
    for(var a=0;a<20;a++)
      o.a();
  }
  var l =   function (ob) { return function () {
    for(var a=0;a<20;a++)
      ob.a();
  };}(o)

  function q(){
    for(var a=0;a<20;a++)
       v();
  }

  function s(){
    var u = v;
    for(var a=0;a<20;a++)
       u();
  }
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
Local Scope Fn
x();
ready
Local Var Fn
w();
ready
Cached Local Scope Fn
y();
ready
Window
z();
ready
Cached Window
d();
ready
Obj
p();
ready
Cached Obj
l();
ready
Global
q();
ready
Cached Global
s();
ready

Revisions

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