Global Variables vs Local Variables (v54)

Revision 54 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>
  var a,b=0;
  function x() {
    for(a=0;a<20;a++)
      b+=a;
  }

  function w() {
    for(this.a=0;this.a<20;this.a++)
      this.b+=this.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 myTest() {
var g = this;
    for(g.a=0;g.a<20;g.a++)
      g.b+=g.a;
  }

var myTest2 = (function(window){  
var myTest22 = function(){   
 for(window.a=0;window.a<20;window.a++)
      window.b+=window.a;
  }
return myTest22;
})(window);

var myTest3 = (function(g){  
var myTest22 = function(){   
 for(g.a=0;g.a<20;g.a++)
      g.b+=g.a;
  }
return myTest22;
})(this);
</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
new
myTest();
ready
new2
myTest2();
ready
new3
myTest3();
ready

Revisions

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