Resources about d3 specifically.

D Attribute
A short introduction into the the d attribute of path elements
Updating your chart in d3.js
How v5 helps clean up your updating code
Learn all the things that are important about projections in d3.
How to create a simple tooltip in d3.js
Learn how to create tooltips in d3. This post shows you actual d3 code and adds explanations to the most important aspects of tooltips in d3 and has a demo as well.
SVG Basics for d3
Three basic elements of SVG you should know if you want to create maps with d3.

Library Comparisons

Articles and Resources about different libraries.

Comparison of Mapbox GL JS and D3.js
How do d3.js and Mapbox GL JS compare? Which library shines on which front? And who will score the most wins? I compare these two libraries on amount of code, simplicity of setup, and much more.
Feature Comparison of Online Mapping Libraries
An overview of features from the top mapping libraries.


List of books I recommend for learning d3.

Interactive Data Visualization for the Web: An Introduction to Designing with D3, Scott Murray
Best entry level book that is available. I used the first version a lot to look up things. Highly recommended.
D3.js in Action, Elijah Meeks
Have not read it myself but heard good things and is always recommended by others
Storytelling with Data: A Data Visualization Guide for Business Professionals, Cole Nusbaumer
Not a d3.js book, but a great read for all things Data Visualization and where to focus your attention creating visualizations.
These are affiliate links.