We'll be releasing our new tutorial-based book Fullstack D3 and Data Visualization in a couple of weeks: https://www.fullstack.io/fullstack-d3

Not a course per se, but you can definitely learn a lot by tweaking preexisting code found on https://observablehq.com.

I made a free course that teaches D3+React: https://webvis.paulbutler.org/

I wrote it to accompany an in-person class I teach at work, but it's meant to work standalone as well.

Check out the course Learning Data Visualization with D3.js on Lynda.com at http://www.lynda.com/D3-js-tutorials/Learning-Data-Visualiza....

Anything by Shirley Wu.

Freecodecamp.org has a module on data visualization that's based on d3.