A couple of months ago, we all saw how powerful d3.js is an how we can create some awesome dashboards in SharePoint.
I just found a video training course on d3 on Egghead.io. It appears to be free so check it out. From what I’ve watched so far, it gets into using the library on Node.JS but you can adapt it to using in SharePoint.
Here’s the link to the training! https://egghead.io/lessons/d3-install-and-configure-d3-v4?course=build-interactive-javascript-charts-with-d3-v4