I’ve been looking at source maps recently. The reason for this is that I want to be able to pass some code through a pipeline of transformations, but still maintain sourcemaps so that you get the nice debugging behaviour.
The specification for source maps talks about VLQ as if it’s a well known thing, and perhaps it is – apparently it’s part of the MIDI spec and the wikipedia page is entirely focussed on that implementation. I finally found a bit more detail from Peter van der Zee on exactly how it works and was able to create my own decoder.
As part of that, I got into a discussion about whether it was possible to use dynamically generated source maps. The result of my investigation is on github here.