each.js

        // Collection iterator
        self.each = function(_collection, _callback) {
            var method, index, item, collection, keys, wrapper, 
                index_r = "i", 
                item_r = "_collection[i]", 
                collection_r = "_collection";

            // Normal collection
            if(_collection.length > 0 || _collection instanceof Array) {
                method = true;
                wrapper = "for(var i=0, len=_collection.length; i<len; i++) {";
            }
            
            // Object collection iterate using Object.keys 
            if("keys" in Object && !method) {
                keys = Object.keys(_collection);
                if(keys.length > 0) {
                    index_r = "keys[i]";
                    item_r = "_collection[keys[i]]";
                    wrapper = "for(var i=0, len=keys.length; i<len; i++) {";
                    method = true;
                }
                else {
                    method = false;
                }
            }

            // Object collection (iterate over properties)
            if(!method) {
                wrapper = "for(var i in _collection) { if(!_collection.hasOwnProperty(i)) continue; "; 
            }

            // Get function source
            var callback = _callback.toString(),
                // Isolate the function body and the parameters
                body = callback.substring( callback.indexOf("{")+1, callback.lastIndexOf("}") ),
                params = callback.substring( callback.indexOf("(")+1, callback.indexOf(")", callback.indexOf("(")+1) ).split(",");

            // Map the index parameter
            if(typeof params[0] === "string" && params[0].length) {
                index = params[0].replace(whitespace, '');
                body = body.replace(new RegExp("\\b"+ index +"\\b","g"), index_r);
                // Map the item parameter
                if(typeof params[1] === "string") {
                    item = params[1].replace(whitespace, '');
                    body = body.replace(new RegExp("\\b"+ item +"\\b","g"), item_r);
                    // Map the collection parameter
                    if(typeof params[2] === "string") {
                        collection = params[2].replace(whitespace, '');
                        body = body.replace(new RegExp("\\b"+ collection +"\\b","g"), collection_r);
                    }
                }
            }

            // Map all context instances and returns
            body = body.replace(replace_this, item_r);
            body = body.replace(replace_return, "break");
            
            // Create the loop and execute it
            eval(wrapper + body +'}');
            return _collection;
        };