To end on a somewhat pedantic note--before adding any interaction to any project, ask whether it actually needs it. If you are in the cohort of folks using D3 as a means to generate data visualizations for news media, realize that the number of people who actually use interactive graphic functionality is depressingly small; most readers will simply flick right past the elaborately-designed interactive graphics you spent all that time on. New York Times Deputy Graphics Editor Archie Tse provides three rules for visual storytelling:
- If you make the reader click or do anything other than scroll, something spectacular has to happen.
- If you make a tooltip or rollover, assume that no one will ever see it. If content is important for readers to see, don't hide it.
- When deciding whether to make something interactive, remember that getting it to work on all platforms is expensive.
The source is at https://github.com/archietse/malofiej-2016/blob/master/tse-malofiej-2016-slides.pdf.
In fact, my team at the Financial Times very seldom make our graphics interactive as it tends to detract from what the graphic is actually trying to convey:
FT Interactive News Head Martin Stabe says information visualization is meant to clarify data, but too much interactivity hinders understanding by transferring responsibility from the designer to the reader to work out the important points.
Source (paywalled) is at https://www.ft.com/content/c62b21c6-7feb-11e6-8e50-8ec15fb462f4.
One solution around this is to attach interactivity to browser scroll events, leading the user through the data as they scroll, but even this is somewhat fraught with peril as it's somewhat difficult to get right, and some people just resent having their scrolling hijacked. The WSJ's scroll-watcher library might be one possibility if you intend to implement a "scrollyteller"-style interactive graphic. See https://github.com/WSJ/scroll-watcher.
Lastly, even if you're not designing for a news audience, realize that it's worth being very careful about how you build interfaces. Although you, as a developer, have quite high computational skills, the vast majority of people don't - in fact, a recent study looking into computing skills among OECD nations found that a full 24% are totally unable to use a computer effectively, with another 16% having only the most basic of skills (Refer to https://www.nngroup.com/articles/computer-skill-levels/). Particularly if you're working in government and using D3 to convey information important to your constituents, keeping interaction to a minimum is often a very good idea.