Lauren both introduces the making of p5js and demonstrates how totally cool p5js is, highlighting some of it best features.
The OpenProcessing site is a gallery of the amazing projects that have been made with Processing and p5js.
(Slightly confusingly, p5js is the modern Javascript version of Processing. Processing itself is java-based)
Not only is this site inspirational, you can also view the source code, and remix any project you like to develop your own version.