Great news. We already had parchment.js - but with this you can use images in your interactive fiction. One day I made a website in parchment, it's a more narrative way of engaging the audience, I thought it would be nice to use pictures (low bandwidth black and white Filter Lite dithering). Javascript kills SEO though (I could use something like PhantomJS to simulate all pages into static html).

This comes from Zarf, someone who deeply cares about IF and the way it is told and experienced.

There's another JS IF VM similar to Quixe with a different IO layer. Quixe uses the Glk IO layer while Glulx-Typescript (github) decouples the IO by providing a pipeline of NVPs to the web app. Also it's written Typescript. It is a Glulx engine, but as I said, it only delivers data to the web app. All the UI/UX has to be created by the author.

I'm still (slowly) working on a proof of concept story and have an author-partner to help out. The long-term goal is to have JS tools to template an IF story, use Inform 7 to write it, and have the tools rebuild automatically, and the author would have a browser showing the results as they work.

I blog about it and other things at: http://plover.net/~dave/blog.

Does it handle the old Z-machine formats?

No but if you have the source you can recompile the zcode sources to glulx. But you could run z-machine with parchment (which supports zcode without images) http://iplayif.com/ Parchment doesn't support the rare z6 images when I asked in 2009 https://groups.google.com/forum/#!topic/parchment/RsLytfu5JI...

The z-machine and glulx are two different virtual machine specifications. Glulx supports 32-bit, which allows for much larger stories than Z stories.