Iterator Pattern

gistfile1.js

// http://shichuan.github.com/javascript-patterns/

var agg = (function(){
     var index = 0;
     var data = [1, 2, 3, 4, 5];
     var length = data.length;
     return {
          next : function(){
               var element;
               if(!this.hasNext()) return null;
               element = data[index];
               index = index + 2;
               return element;
          },
          hasNext : function(){
               return index < length;
          },
          rewind : function(){
               index = 0;
          },
          current : function(){
               return data[index];
          }
     };
}());

while(agg.hasNext()){
     console.log(agg.next());
};

agg.rewind();

console.log(agg.current());