Prevents the next button from proceeding to the next question if the user has not provided a valid input, such as not selecting a star-rating.
Cleaned up the product.js's switch statement and reorganized file for readability.
Progressing forward and backward in the rate.html both stores the value (courtesy of Tony, and cleaned up a bit by myself for better readability) and selects the options for the opinion, familiarity, and star rating questions. I may consider putting that into a seperate function on its own. There wasn't error-handling in that one. What's left for rate.html is to handle the JSON handling but first, survey.html may require to send its data to rate.html, to be done by Tony. Good night everyone; we're almost there.