Results on Chrome

1. var start=(new Date()).getTime();
   for(var i=0;i<1000000;i++){
       function fn1(){
           return "Traditional approach";
       }
   }
   var end=(new Date()).getTime();
   console.log(end-start);

   Test 1: 946 milliseconds. Test 2: 950 milliseconds.

2. var start=(new Date()).getTime();
   for(var i=0;i<1000000;i++){
       var fn2 = function(){
           return "Using var keyword";
       }
   }
   var end=(new Date()).getTime();
   console.log(end-start);

   Test 1: 1476 milliseconds. Test 2: 1476 milliseconds.

3. var start=(new Date()).getTime();
   for(var i=0;i<1000000;i++){
       window.fn3 = function(){
           return "As a member of window object";
       }
   }
   var end=(new Date()).getTime();
   console.log(end-start);

   Test 1: 1809 milliseconds. Test 2: 1808 milliseconds.