Global Variables vs Local Variables (v47)

Revision 47 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>
/*
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.
*/
  var a,b,c,d,g,h=0;
  function x(){for(a=0;a<20;a++){b+=a}}
  function w(){for(window.a=0;window.a<20;window.a++){window.b+=window.a}}
  function y(){var c,d=0;for(c=0;c<20;c++){d+=c}}
  function z(){var c=a,d=b;for(c=0;c<20;c++){d+=c}}
  function v(global){for(global.c=0;global.c<20;global.c++){global.d+=global.c}}
  function p(e,f){for(e=0;e<20;e++){f+=e}}
  function t(e,f){var c=e,d=f;for(c=0;c<20;c++){d+=c}}
  function q(){ if (q.c === undefined) { q.c = q.d = 0};for(q.c=0;q.c<20;q.c++){q.d+=q.c}}
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
Global variables
x();
ready
Local variables
y();
ready
Cached global variables
z();
ready
Window
w();
ready
window param
v(window);
ready
global var as param
p(g,h);
ready
cached global var param
t(g,h);
ready
t(window.g,window.h);
ready
p(window.g,window.h);
ready
Test 10
q();
ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.