Is it still relevant today to use Processing.js to create interactive animations/visualizations on the web?

Question

JavaScript

Is Processing.js being used today, or is this one considered deprecated and better to use alternatives like three.js for example?
What are the pros/cons?
I found a very good and in-depth book on creating various interactivity for the web, it clearly describes where and what mathematics / physics to use for this or that functionality - natureofcode.com/book . All examples in this book use processing.js. Is it worth learning this engine or is it better for practice to choose another (more supported, widespread)?