I would like to store freely formatted (JSON, XML, CSV) d3 data sets back to a database, preferably using (for the sake of consistency) native d3 methods.
Is this already catered for in d3, and if not, can existing d3.js methods be coaxed into handling this?
Examples would be welcome.
This isn't something that you can do with Javascript -- there's no direct access to things like databases. This is not a restriction of d3, but Javascript itself. What you can do is post data to a server which will then add it to a database. There's no support in d3 for that though, only for retrieving data.
There are plenty of other Javascript libraries though that allow you to post data to a server, for example jquery.