Earlier quoted context omitted.
Supported across all major browsers :) We've covered much ground on the most used charts (while the heatmap just happened to be something we needed) and have the basic components down. That'll facilitate putting in, say, more axis charts in future. We're sure of not running out of ideas, there are just so many chart types out there :D
Do you have a separate repo with unit tests? If not, how do you test the charts?
We look forward to adding those (just created an issue). They are quite decoupled as of now, so shouldn't be much trouble.