[all components] Support lazy element in `render` prop by oliviertassinari · Pull Request #3856 · mui/base-ui

oliviertassinari · 2026-01-25T00:54:29Z

Fix #2859. See #2859 (comment) for why a fix. With this PR release, we could then merge shadcn-ui/ui#9444.

You can test this work / the problem in the playground using:

import * as React from 'react';
import { Button } from "@base-ui/react/button"

// A "Fake" component to be loaded
const FakeComponent = (props) => <div style={{ color: 'red' }} {...props} />;
// A "Lazy" version that resolves after 100ms
const LazyMock = React.lazy(() => {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve({ default: FakeComponent });
    }, 0);
  });
});

const AsyncServerComponent = async (props) => <div style={{ color: 'blue' }} {...props} />

export default function CloneElement() {
  return (
    <div>
      <React.Suspense fallback={<div>Loading…</div>}>
        Cases
        <Button nativeButton={false} render={<LazyMock />}>
          Lazy
        </Button>
        {/* <Button nativeButton={false} render={(props) => <LazyMock {...props} />}>
          Lazy function
        </Button> */}
        <Button nativeButton={false} render={<AsyncServerComponent />}>
          Async
        </Button>
        {/* <Button nativeButton={false} render={<React.Fragment>Bar</React.Fragment>}>
          Framgnet
        </Button> */}
        {/* <Button nativeButton={false} render={<React.Fragment><div>1</div><div>2</div></React.Fragment>}>
          Array
        </Button> */}
      </React.Suspense>
    </div>
  );
}

While I was at it, I tried to bring it to the next step. There were easy, low-hanging fruits 🍇:

Tests

I have added some missing test cases for useRenderElement().

Error recovery

I have added logic to help developers when they provide wrong values to the render prop.

Before, if you did this: <Button nativeButton={false} render={<React.Fragment>Bar</React.Fragment>}>, the error would be confusing:

now, you get something clearer. I love it 😌:

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pkg-pr-new · 2026-01-25T00:55:36Z

base-ui-tanstack-start

vite-css-base-ui-example

pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@3856

pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@3856

commit: 34e7d17

mui-bot · 2026-01-25T00:56:09Z

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui/react	🔺+89B^(+0.02%)	🔺+52B^(+0.04%)

Details of bundle changes

Check out the code infra dashboard for more information about this PR.

netlify · 2026-01-25T00:57:35Z

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atomiks

Nice that there's a workaround 🙌 Have some notes:

atomiks · 2026-01-25T11:01:12Z

packages/react/src/utils/useRenderElement.tsx

+          `Base UI: Expected to receive a valid React element in the "render" prop but received an invalid one.`,
+        );
+      }
+    }


Could this error message be more helpful? e.g. why is it invalid, how to fix it.

Ok, I tried to do something better, applying:

https://www.notion.so/mui-org/DevEx-Technical-writing-style-guide-7e55b517ac2e489a9ddb6d0f6dd765de?source=copy_link#85219822c3194b6f8a49ee08ea82b90a closer to the letter

and [all components][docs-infra] Update all error messages to have docs page? mui-public#222

Suggestion, add error writing style in your AGENTS.md like mui/material-ui#47668 so that review bots can suggest improvements.

packages/react/src/utils/useRenderElement.tsx

packages/react/src/utils/useRenderElement.test.tsx

Signed-off-by: atomiks <cc.glows@gmail.com>

Janpot · 2026-01-26T11:45:31Z

packages/react/src/utils/useRenderElement.tsx

+    // so we can throw before with custom message.
+    if (process.env.NODE_ENV !== 'production') {
+      if (!React.isValidElement(newElement)) {
+        throw /* minify-error-disabled */ new Error(


Why not just remove that [].join('\n')?

We don't need to minify the error, it won't run in production.

Right, but why not write error messages according to the same rules, regardless of whether there's a production guard around? And why does it matter that this error does not get minified?

Anyway, we can probably automate this check like in mui/mui-public#794

but why not write error messages according to the same rules

Fair point

why does it matter that this error does not get minified?

We still need /* minify-error-disabled */ to ignore that error.

Taking care of non-prod errors in mui/mui-public#1069

atomiks · 2026-01-26T11:54:02Z

Possibly related to this: support for a render function that returns a lazy component:

<Component render={<Lazy />} />
<Component render={(props) => <Lazy {...props} />} />

oliviertassinari · 2026-01-26T14:06:24Z

Possibly related to this: support for a render function that returns a lazy component:

@atomiks AFAIK, this already work; it doesn't go through the .cloneElement() code path. I have updated this PR's description playground, and I could see it working.

oliviertassinari requested review from atomiks and colmtuite as code owners January 25, 2026 00:54

oliviertassinari added the type: bug It doesn't behave as expected. label Jan 25, 2026

oliviertassinari requested a review from michaldudak as a code owner January 25, 2026 00:54

oliviertassinari added external dependency Blocked by external dependency, we can’t do anything about it. scope: all components Widespread work has an impact on almost all components. labels Jan 25, 2026

greptile-apps bot reviewed Jan 25, 2026

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oliviertassinari mentioned this pull request Jan 25, 2026

[all components] render prop doesn't work with async components #2859

Closed

oliviertassinari force-pushed the fix-clone-element-async branch from 0e36d98 to f41510f Compare January 25, 2026 00:57

oliviertassinari force-pushed the fix-clone-element-async branch 2 times, most recently from 47b1626 to 38d0fa0 Compare January 25, 2026 00:59

oliviertassinari removed request for atomiks and colmtuite January 25, 2026 01:02

oliviertassinari force-pushed the fix-clone-element-async branch from 38d0fa0 to 3d6972e Compare January 25, 2026 01:12

This was referenced Jan 25, 2026

fix: remove unnecessary Base UI use client v2 shadcn-ui/ui#9444

Open

[bug]: Base UI Button being 'use client' means you can't import buttonVariants in non-client components shadcn-ui/ui#9428

Open

[all components] Support Lazy element in render={}

49dccc7

oliviertassinari force-pushed the fix-clone-element-async branch from 3d6972e to 49dccc7 Compare January 25, 2026 01:30

atomiks reviewed Jan 25, 2026

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oliviertassinari added 2 commits January 25, 2026 15:44

reduce bundle size

19c7a3d

improve a bit the error message

842ea90

oliviertassinari force-pushed the fix-clone-element-async branch from 82bcea8 to a227d2b Compare January 25, 2026 17:09

oliviertassinari added 2 commits January 25, 2026 18:18

improve error message

570f715

last piece

c5457e7

oliviertassinari force-pushed the fix-clone-element-async branch from a227d2b to c5457e7 Compare January 25, 2026 18:01

oliviertassinari mentioned this pull request Jan 25, 2026

[code-infra] Fix dection of new Error() that can't be minified mui/mui-public#1067

Closed

atomiks reviewed Jan 25, 2026

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packages/react/src/utils/useRenderElement.tsx Outdated Show resolved Hide resolved

atomiks reviewed Jan 26, 2026

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packages/react/src/utils/useRenderElement.test.tsx Outdated Show resolved Hide resolved

Apply suggestions from code review

5250459

Signed-off-by: atomiks <cc.glows@gmail.com>

atomiks approved these changes Jan 26, 2026

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atomiks added 2 commits January 26, 2026 22:36

Merge branch 'master' into fix-clone-element-async

d1639ba

Merge branch 'master' into fix-clone-element-async

34e7d17

Janpot reviewed Jan 26, 2026

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atomiks changed the title ~~[all components] Support Lazy element in render={}~~ [all components] Support lazy element in render prop Jan 26, 2026

atomiks merged commit 50e164e into mui:master Jan 26, 2026
21 of 23 checks passed

oliviertassinari deleted the fix-clone-element-async branch January 26, 2026 13:54

atomiks pushed a commit to atomiks/base-ui that referenced this pull request Jan 28, 2026

[all components] Support lazy element in render prop (mui#3856)

97a4159

brijeshb42 mentioned this pull request Jan 29, 2026

[code-infra] Setup unified changelog generation #3711

Merged

1 task

atomiks mentioned this pull request Feb 11, 2026

[bug?][help] how do you use render props in Next.js? #4045

Closed

oliviertassinari mentioned this pull request Mar 25, 2026

fix: remove unnecessary Base UI use client shadcn-ui/ui#10167

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