The latest version of all major browsers support C/C++/etc code compiled to WebAssembly http://webassembly.org/ ("wasm") format, in addition to the older "asm.js" style of compilation targeting a subset of JavaScript directly.

As far as I know the first library that MediaWiki uses to support WebAssembly is ogv.js, my codec & playback library which we use for playing media on Safari, IE, and Edge. ogv.js is packaged with the TimedMediaHandler extension, and we've used its asm.js mode for about two years now.

I'd like to enable the WebAssembly mode in production for the faster compilation times, but want to double-check that we've established some best practices for WebAssembly usage first.

https://phabricator.wikimedia.org/T181451 -- I've started up a provisional RFC, currently more of a document with a few pain points called out:

* packaging (check in binaries from a library, or use a package manager like npm?) * loading (loading .wasm or .js files as assets, vs what can use RL) * security (where to concentrate for security reviews, etc)

This may grow into a recommendation on how to package & load things and some tweaks to RL. If anybody has any questions about the scariness that is wasm, give a shout. I want to make it not-too-scary. :)

-- brion