1  <script type="text/javascript">   
 2         var a = 10;
 3        
 4         var Bar = (function () {
 5             console.log(a); //undefine
 6             var a = 20;
 7             return function () { a += 1; console.log(a); };
 8         })();
 9         Bar();
10         Bar(); 
11 </script>