workshopper | A terminal workshop runner framework | Learning library

I am trying to solve the sixth problem of learnyounode which needs a module file to print file list. Here are my two files:

The main file program.js:

I'm attempting to redefine Javascript's reduce using a recursive function. Here's my attempt, which doesn't work. If anyone can change it only slightly to make it work, that would be great because I'd understand it better. (This is an exercise in functional-javascript-workshop).

I'm trying to make write a node program that will read a file director and filter out those without a certain file extension. (This is a challenge for learnyounode) For some reason it adds to the list 'undefined'. Can anyone tell me why?

I am learning node by doing learnyounode exercises from nodeschool. In the 8th exercise they ask to write a program which does the following:

• takes three URLs as arguments,
• collects data from responses,
• prints them to the console in the same order as in the arguments.

They briefly mention the existence of async libraries which help with counting callbacks but they also invite to complete the exercise without them. My initial solution then was the following: