Is React 19 Required for Vike-React?

[dajinchu]

Does vike-react and react-streaming require react 19+? The peerDeps say so, but so far things are working with react 18. Want to verify if there's any gotchas with sticking with 18.

[brillout]

What's your motivation to stick to React 18? I was under the impression that React 19 is mostly backwards compatible, so I didn't prioritize React 18 support.

[dajinchu]

I just have a large codebase that requires substantial work to upgrade to React 19, mostly due to reliance on some very old npm packages. We're in the process of the upgrade already, but just wanted to check if there was any major, specific reason for react 19 requirement. We're considering releasing with 18 while we continue the upgrade to 19.

[brillout]

I'm open for vike-react to officially support React 18 for a longer time, but I'd need more information: what npm packages aren't supporting React 19?

FYI the overall idea is that Vike core is rock-solid and stable while vike-react is moving slightly faster. The idea being that vike-react is easy to fork (it's only 1k LoC) so that supporting (very) old React versions is relatively easy if needed.

If the latest vike-react version is working with React 18 then consider simply pinning vike-react while being careful when updating vike-react.

[dajinchu]

eg. react-stripe-elements, enzyme. Both deprecated 5+ years ago.

Such old packages of course just need to be upgraded out of, but for any large code base it just takes time that we don't always have.

As we are most of the way through the upgrade already, I don't think there's any need for me personally for vike-react to officially support React 18. We're OK pinning and testing against a version of vike-react while we finish the React 19 upgrade, like you said.

[brillout]

Sounds good, and I see. Don't hesitate to let me know if you do end up anything from our side.

FYI, IIRC, the only soft dependency on React 19 is some React 19 only argument (onUncaughtError) passed to React's ReactDOM.hydrateRoot() and ReactDOM.createRoot() inside +onRenderClient — thus, React 18 should be fine for the time being (the onUncaughtError handler is only about prettifying errors and adding support for throw render/redirect inside React components).