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bellard / quickjs

Public repository of the QuickJS Javascript Engine.
https://bellard.org/quickjs
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Question: features needed for React #290

Open ancorgs opened 4 months ago

ancorgs commented 4 months ago

This is not really an issue, just a question.

As you know, React is one of the most popular frameworks for developing web applications nowadays.

On the other hand, I have seen a couple of browsers that rely on QuickJS for adding Javascript support (elinks, chawan...)

I was wondering if there would be any chance to make React applications work at such browsers.

According to React's documentation, it relies on these modern Javascript features:

So the first question to solve is whether QuickJS supports all those features. I found information about promises but I'm not sure about the other two.

saghul commented 4 months ago

QuickJS supports all of those. From a JS prespective I'm not sure what would be missing, aside from, obviously, the DOM.

andrieshiemstra commented 4 months ago

I played with it some, implemented a simple DOM but I don't think it's actually needed for SSR to work...

https://github.com/HiRoFa/GreenCopperCmd/blob/main/scripts/ssr.ts

chqrlie commented 4 months ago

I played with it some, implemented a simple DOM but I don't think it's actually needed for SSR to work...

https://github.com/HiRoFa/GreenCopperCmd/blob/main/scripts/ssr.ts

SSR (server side rendering) is not the issue, the client side code of React applications should be transpiled to standard javascript that QuickJS supports. The DOM implementation is provided by the navigator and must be accessible from javascript as host objects.

bptato commented 4 months ago

QJS itself is fairly complete. Most significant omission I've found so far is that it has no global proxies, so WindowProxy may be impossible to implement. I haven't tried too hard, though, and I doubt it's really needed for React.

However, to get complex JS pages running, you also need to implement lots of web APIs. Of these, Chawan is missing XHR, proper CSSOM, many Event types, etc. I can't speak for Elinks, but I suspect the situation is similar over there, with at most differences in which APIs are missing.

To figure out what exactly you'd need, you can do the following:

If you're lucky, the missing API is something fairly simple, like an attribute reflector. If you're less lucky, it depends on a gazillion other APIs, which may require structural changes in the browser. If you're even less lucky, no JS will run at all, because the browser is not running something, e.g. module scripts, or some event.

In some cases, it might even be a bug in QJS. e.g. I stumbled upon a bug recently that indirectly broke old.reddit comment collapsing. But it happens very, very rarely.