Possibility of replacing NodeJS with QuickJS in the Firefox build system

[glaubitz]

Modern versions of Firefox require NodeJS to build which is employed during the build process to transpile some JavaScript files.

Since the set of architectures supported by NodeJS is rather limited due to Google gatekeeping what architectures they want to support in V8, I was wondering whether it would be possible that QuickJS could replace NodeJS in the Firefox build system so that Firefox itself can be built on a wide variety of architectures again?

Are there any fundamental limitations in QuickJS as compared to NodeJS or should the former in general be able to replace NodeJS in the Firefox build system?

Please see also this discussion in the Linux for SPARC issue tracker on this question,

[glaubitz]

I have used the following simple wrapper script now to invoke QuickJS as a NodeJS replacement:

(sid_sparc64-dchroot)root@stadler:/# cat /usr/bin/node
#!/bin/bash

set -e

VERSION="v20.19.6"

if [ "$1" = "--version" ] ; then
  echo $VERSION
  exit
fi

/usr/bin/qjs $@
(sid_sparc64-dchroot)root@stadler:/#

However, this fails with the following syntax error:

Executing "/usr/bin/node /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/shared/build/build.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/ast.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/breakpoints.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/event-listeners.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/exceptions.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/expressions.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/index.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/pause.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/pending-breakpoints.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/quick-open.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/source-actors.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/source-blackbox.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/sources.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/sources-content.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/sources-tree.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/tabs.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/threads.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/tracer-frames.js /home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/debugger/src/reducers/ui.js /home/glaubitz/firefox-new/firefox-146.0.1/build-browser//dist/bin/browser/chrome/devtools/modules/devtools/client/debugger/src/reducers"
b"ReferenceError: 'require' is not defined\n    at <eval> (/home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/shared/build/build.js:14:15)\n\n"
b"ReferenceError: 'require' is not defined\n    at <eval> (/home/glaubitz/firefox-new/firefox-146.0.1/devtools/client/shared/build/build.js:14:15)\n\n"

Is this a known problem maybe?

[andrieshiemstra]

Hi @glaubitz,

Quickjs is purely a script engine, like v8 (which is used by nodejs)

Functions like 'require' (part of the CommonJS module system) are implemented by NodeJs, not by the script engine (and thus also not by quickjs).

And even if you do implement a require function (which is relatively simple) you'll find the build.js of firefox uses more NodeJs features and modules like

const fs = require("fs");
const _path = require("path");

Quickjs does have file functions of its own like os.mkdir and such but that will require changes to build.js to function.

There are projects which implement more of the WinterCG spec like txiki.js but I'm not sure require is part of that spec.

Btw, Node seems to be used just for transpiling with babel, why not just use something like swc?

[glaubitz]

Thanks a lot for the explanations! I'm a complete novice when it comes to JavaScript, so I'm doing a lot of trial and error at the moment and depend on more experienced people to help me what I'm doing wrong. ;-)

If the Rust-based Deno or SWC can be used to replace NodeJS, I think Mozilla would be likely to use them as Rust is at the core of Firefox these days.

I have never used either of them, do you know how to invoke them for Firefox?

[andrieshiemstra]

@glaubitz
deno uses v8, so that won't fix your issue (was a bad idea from me)

node.py seems to call node build.js and build.js uses babel to transpile.

instead of calling build.js you could call build-js.sh which in turn is build.js rewritten to a shell script which uses swc.

I haven't checked if swc works on sparc archs and such..

Looking at the build.js, rebuilding it to support quickjs should also be farely doable.

[glaubitz]

deno uses v8, so that won't fix your issue (was a bad idea from me)

Yeah, I just realized that when I tried building Deno on SPARC ;-).

instead of calling build.js you could call build-js.sh which in turn is build.js rewritten to a shell script which uses swc.

Wait, Firefox already uses swc or am I missing something?

Looking at the build.js, rebuilding it to support quickjs should also be farely doable.

Ah, so the whole issue revolves just around build.js in Firefox?

[andrieshiemstra]

no there are also unit tests which use node, and a test which sets up a node http2 server for something, and probably more...

[glaubitz]

Hmm, ok. I guess the tests could be skipped when building for exotic platforms.