[Bug]: Component prop stopped working on v6.11.0

[diegohaz]

What version of React Router are you using?

6.11.0

Steps to Reproduce

Visit https://stackblitz.com/edit/github-ceeupc?file=src%2FApp.tsx

Expected Behavior

Route components passed to the Component prop are rendered:
https://stackblitz.com/edit/github-ceeupc-vzvsw6?file=src%2FApp.tsx

Actual Behavior

Route components passed to the Component prop aren't rendered.

[timdorr]

@brophdawg11 Did #10287 break this?

[JasperHorn]

I was wondering why my application suddenly wasn't working the way it should anymore...

[brophdawg11]

Hm, yeah, this is a bit of a miscommunication. Component/ErrorBoundary were really only intended for RouterProvider usages but we weren't clear on that in release notes or docs 😕 . The initial implementation did technically allow usages with BrowserRouter, but at the expense of re-rendering every single time even if nothing changes due to how React works under the hood.

For example, Layout will not re-render when navigating between Home/About here (assuming it doesn't pull from RR contexts) because React.createElement is called initially up front and the same ReactElement instance can be re-used across renders.

<Routes>
  <Route path="/" element={<Layout />}>
    <Route index element={<Home />} />
    <Route path="about" element={<About />} />
  </Route>
</Route>

However, if you use Component, then Layout will re-render on every navigation no matter what. This is because React.createElement is called at render time so we create a new ReactElement identity every time and it can never re-use across renders.

<Routes>
  <Route path="/" Component={Layout}>
    <Route index Component={Home} />
    <Route path="about" Component={About} />
  </Route>
</Route>

The reason Component can work in RouterProvider is that we can internally call createElement up front and store the ReactElement instance inside the router so it can avoid re-renders.

We could add support back - but it's a pretty significant de-optimization to use Component in BrowserRouter apps so I don't think we necessarily want to encourage that. But in the spirit of SemVer, this probably would fall under regression and deserve a fix.

@diegohaz and @JasperHorn What do you folks think? Would you want Component support back knowing the performance implications?

[diegohaz]

For my use case, I can move back to element. I used Component because it seemed like a more straightforward API. Thanks for the clarification.

[JasperHorn]

I was working on an older application that I hadn't written myself, and I had recently moved it to recent version of react-router. For this, I can move to using element without too much effort - the effort was in finding out why it wasn't working.

You could revert in 6.11.1 and continue in 7.0.0. But I also see why you might not want to bump the major version just for this...

[happylolonly]

We also had not obvious issue while build, I would also use Component, it looks more clear.

cyberia-to/cyb-ts@64cd4dc

In docs it is written as it is the same behavior.

[brophdawg11]

This is fixed by #10434 and should be available once 6.11.1 is released