Pergunta de entrevista da empresa HubSpot

First guy had me do simple stuff in jQuery that resembled a basic Twitter app. If you can create a simple Twitter clone in just jQuery you'll be set. Second guy asked me to build a simple function that could be done using a while loop then cover the edge cases. Last guys you built more simple functions like given a string, add a comma between each letter except the last. Know how to add things to the prototype.