Plain Code

/**
 * AOP framework for aspect oriented programming in JavaScript
 */
 
 var AOP = AOP || function() {

     //Private methods

     function toArray(iterable) {
         if (!iterable) return [];
         if (iterable.toArray) return iterable.toArray();
         var length = iterable.length || 0, results = new Array(length);
         while (length--) results[length] = iterable[length];
         return results;
     }


     //Public methods

     var public = {
         around: function(obj, fname, advice) {
             var oldFunc = obj[fname];
             obj[fname] = function() {
                 var args = [oldFunc].concat(toArray(arguments));
                 return advice.apply(this, args);
             };
         },

         before: function(obj, fname, advice) {
             var oldFunc = obj[fname];
             obj[fname] = function() {
                 var args = [oldFunc].concat(toArray(arguments));
                 advice.apply(this, args);
                 return oldFunc.apply(this, arguments);
             };
         },

         after: function(obj, fname, advice) {
             var oldFunc = obj[fname];
             obj[fname] = function() {
                 var args = [oldFunc].concat(toArray(arguments));
                 oldFunc.apply(this, arguments);
                 return advice.apply(this, args);
             };
         },
         
         callMethod: function(args) {
             var argsArray = toArray(args);
             return argsArray[0].apply(this, argsArray.slice(1));
         }
     };

     return public;
 }();