From Scott Murray - alignedleft.com

These tutorials evolved out of my own process of learning how to use D3. You already know that D3 is an extraordinary tool for mapping data within web pages, written by Mike Bostock. Many people, including myself, come to D3 with backgrounds in design, mapping, and data visualization, but not programming and computer science.

Yet D3 employs advanced JavaScript techniques, so learning to use D3 often means learning a lot about JavaScript. For many datavis folks, D3 is their introduction to JavaScript. It’s hard enough to learn a new programming language, let alone a new tool built on that language. D3 is amazing and will enable you to do great things with JavaScript that you never would have even attempted. The time you spend learning both the language and the tool will provide an incredible payoff.

My goal is to reduce that learning time, so you can start creating awesome stuff sooner.