Unfortunately, the API is still not stable, nor is it actually implemented anywhere in the browser. This will constitute a major, breaking API deviation, but until the specification looks stable, I'll continue using the deliverData/deliverEOF combos I've been using.
(For bonus points: work out how to represent the handler of MimeParser with the streams API).
The Streams API is what will (hopefully) come out naturally for things like file or socket I/O, and there are aspirations for being able to pass streams across worker boundaries.
https://streams.spec.whatwg.org/
Unfortunately, the API is still not stable, nor is it actually implemented anywhere in the browser. This will constitute a major, breaking API deviation, but until the specification looks stable, I'll continue using the deliverData/deliverEOF combos I've been using.
(For bonus points: work out how to represent the handler of MimeParser with the streams API).