Single unless you need to use single quotes within quotes. Example let string = "I didn't like it"; You should use .eslintrc with Eslint plugin to help guide you.

Are you talking about storing Cookies or Sessions?

I would start somewhere constructive by address the possible problems and provide possible solutions. This way your showing initiative and confidence.

To narrow down even further where I should start climbing. Would WebGL be optimal to do this effect when you scroll down on this site? http://www.anagram.paris/work/premiereclasse

Thanks Matt Strom , I'll take a look at the Unity doc.

Thanks Marco Alka , It good to have someone that has done the journey give you advice on where to start.

Thanks Ibrahim . That's very insightful.