Compile to WebAssembly

[mafintosh]

Since Node 8 supports WebAssembly it would be nice to compile libsass to that using emscripten so people wouldn't need to compile the c++ or depend on a prebuild.

[xzyfer]

Definitely open to it. We're also about to give napi a shot also. It's an exciting time for native extensions.

[nschonni]

There already is an official libsass Emscripten project https://github.com/medialize/sass.js

[xzyfer]

Yeah but with wasm we can in theory entirely ditch vendor binaries for Node 8+

…

On 10 Jun. 2017 11:54 am, "Nick Schonning" ***@***.***> wrote: There already is an official libsass Emscripten project https://github.com/medialize/sass.js — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2011 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAjZWCpQgdjK6yHR0HJ41REgUVvD7Azvks5sCfdBgaJpZM4N16hz> .

[saper]

Dropping binaries would be fantastic... I wonder how well will that setup perform

[xzyfer]

@mafintosh I'm starting look into this seriously, but I'm struggling with finding resources on how to do this for native extensions in Node. Do you know of any other projects that have made this switch to WASM that I can reference?

[aduh95]

@xzyfer I tried to install the Emscripten SDK on my computer to compile libsass to WASM; good news, it compiles without changing the C++ code!

I follow the following steps:

1. Activate the Emscripten SDK on my environment
2. On the latest commit of libsass, I run the makefile with the Emscripten compiler:

$ make clean && make --eval="CC=emcc
> CXX=emcc"

3. Then I compile the library into wasm: emcc src/*.o lib/libsass.a -O2 -s WASM=1 -o libsass.js

The libsass.wasm file should now contain the library, and can be run by node >=8
Also I try to change the binding.js file of node-sass to use the cross-platform WASM instead of the platform-dependent binary, but I suppose I'm missing something since node displays an error:

In binding.js, I changed:

return ext.getBinaryPath()

by

    return require('./libsass.js'); // libsass.js is the file generated by emcc

And it outputs the following:

TypeError: binding.libsassVersion is not a function
    at Object.getVersionInfo (.../node_modules/node-sass/lib/extensions.js:368:27)
    at Object.<anonymous> (.../node_modules/node-sass/lib/index.js:448:28)
    at Module._compile (module.js:573:30)
    at Object.Module._extensions..js (module.js:584:10)
    at Module.load (module.js:507:32)
    at tryModuleLoad (module.js:470:12)
    at Function.Module._load (module.js:462:3)
    at Module.require (module.js:517:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous>

I hope I'm helping!

[xzyfer]

Thanks for this work @aduh95. You got further than I did when I looked at it. For now I would comment out the binding.libsassVersion code paths to continue making progress.

[kwonoj]

for anyone interested in this topic, I've prepped small poc at #2220 for further discussions.

[xzyfer]

Thank you! I've recently got sassc running as web assembly, but haven't had much luck with node-gyp. I'll take a closer look this weekend.

…

On 19 Jan. 2018 5:41 pm, "OJ Kwon" ***@***.***> wrote: for anyone interested in this topic, I've prepped small poc at #2220 <#2220> for further discussions. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2011 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAjZWHsXziurKG7LXrcgNOfsR2shmt-Xks5tMDkFgaJpZM4N16hz> .

[kwonoj]

For anyone who's interested in this further, I spawned https://github.com/kwonoj/libsass-asm based on my PR #2220 to push this further. So far it passes sass-spec for 3.5.4.

[gijsroge]

I came here after watching @callahad's amazing talk about Webassembly where he mentioned this project's potential for Webassembly.

Thought this might be of interest to the people who are currently putting time in this!

[justrhysism]

Is there a plan to use WebAssembly (libsass-asm) as a replacement for libsass directly? As in, is it being seriously considered? Or are we still in the POC phase?

I periodically run into issues with node-sass/libsass, particularly when switching Node versions because the binaries don't match up. But also, I'd like to remove the network dependency from my toolchain, and currently downloading libsass is the only thing I haven't been able to avoid.

Understand that everyone is busy - feels like we're on the edge of some sort of utopia... it's very exciting (and I can't wait!).

[xzyfer]

Compiling LibSass to WASM is easy. The difficulty is in compiling the C++ code that binds LibSass to Node. This is difficult in part because we need to rely on libuv for async custom importers, and the async render function. This is pretty much where we are stuck right now. The situation may improve when some kind of background worker or threading API lands in WebAssembly.