Better D3 with TDD and E2D3

Bay Area d3 User Group
Bay Area d3 User Group


44 Tehama St · San Francisco, CA




The holidays are a special time of the year. We are all a little more attuned to the generosity of friends, neighbors and co-workers and that awareness tends to spread through our actions. This is spirit the D3 community wants to harbor. The unconf (, held November 21st was a perfect example of what comes together when you bring curious folks out to share ideas in a judgement free environment for the sole purpose of developing ourselves and other around us.

Thank you for being a part of this community.

Our two December speakers and host are no exceptions. Marcos Iglesias ( has been eagerly waiting for a chance to share his knowledge of test driven development for months now. Norihiko is only with us for a moment, before returning to Japan, and doesn’t want to leave without sharing an open-source Excel plug-in you can use to bring D3 into your spreadsheets. Lastly, we have Jared Polivka ( to thank for space at Galvanize ( Jared helps run the SF Data Science ( group and countless other initiative ensuring life-long learners feel welcome.


6:30 Grub and gab

7:00 Marcos: Better D3 charts with TDD

8:15 Norihiko: E2D3

8:30 Lightning talks

9:00 Go home!

Better D3 charts with TDD (approx. 1 hour)

by Marcos Iglesias

When I first started out with D3.js 2 years ago, I built things the same way, customizing examples and although this worked, I was never proud of my code. The chaining of methods makes the charts concise but costs a lot in cognitive overload and maintainability. Building this way is painful to modify, reuse or even to understand once you sit back down after lunch!

I had a huge revelation when I discovered the Reusable API (a modular structure to create and reuse d3 elements) and my code was elevated to even higher levels with Test Driven Development.

In this session, I'll walk you through my journey toward beautiful, maintainable D3 graphs with step by step examples of refactoring crufty code to be shiny and new and testable.

By the end of the talk you too will know how to build decoupled, composable, encapsulated and consistent D3 graphs and be proud of your code again!

E2D3 (approx. 15 minutes)

by Norihiko Sawa

In the last 15 minutes of our night, before lighting talks, Norihiko Sawa will share his work on E2D3. E2D3 is an Open Source project allowing Excel users to bring D3 charts into the world of spreadsheets.

During his talk, you’ll learn how to use the add-in, what’s happening under the hood and how to start adding charts. That’s a lot to cover in 15 minutes. Grab your coffee in advance.

Get a taste of E2D3 by checking out his site E2D3 (