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Thinking with D3.js joins

About this episode

This screencast will get you 100% comfortable with D3 joins. The tutorial is done in such a way that it introduces the concepts to you one at a time, and it's also beginner friendly.

Why you need to understand joins!

D3 is built to work on live data: as your data changes, so does the visualization. Not only does this help with rendering speeds, as it only needs to render the deltas, it also allows you to expose the changes in data to the viewer with transitions and styling.

Starting out with D3 can be a bit of a confusing, and this is largely due to the necessary complexity in the D3 JavaScript API to give us the benefits we get from joins. But once you get your mind around joins, you won't need to look back. This episode introduces the concept to you in little chunks that make it easy to understand not only how the api works, but also how to leverage the power of joins.

Joins make the visualization code more declarative, allowing you to state what should happen when data is introduced, removed or updated, instead of you keeping track of all this state yourself.