can I ask what you expected to get back here?

The Data, as a d3 join. Please correct me if I'm mistaken, but graphics aside (sure I can make it look the same, but that's not the point), the Plot functions (for all that they can do, and are great) only return the svg Node element, and not any of the d3 objects including the data that is associated with all of the objects. If I'm wrong, please let me know. See what my `heatmap2` cell returns below. Expand it and you'll see an array of 13038 SVGRectElement objects, each of which has __data__ associated with it from the original generating data. With this, I can later work with that heatmap2 d3 object interactively to filter, select, highlight, and otherwise manipulate both the data and the visual elements associated with it, including attaching mouseovers and clicks that directly use and pass the currentTarget's data out to other things. My understanding is that the new Plot library just isn't built to do this. But that's why we have the full d3. This example (for students in my class) is highlighting the difference.

thank you for clarifying! I think your conclusion is correct (for now!) interaction is actively being worked on for Plot :) idk if you saw but I submitted a suggestion that would fix an issue with the plot above. namely Plot relies on the input data's types to infer it's scales, so coercing the value to a number would give you a more useful heatmap.