Markdown content starting with "<br/>\n" breaking further parsing

[YanWittmann]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected package

react-markdown@10.1.0, rehype-raw@7.0.0

Steps to reproduce

When starting a markdown content string with <br/>\n, the markdown parsing of the remaining content is skipped and displayed as raw text. Only this exact sequence triggers the behavior, <br/>, \n, \n<br/>, A<br/>\n, etc. cause no issues.

I use the ReactMarkdown component with rehype-raw to properly enable HTML content, but I was able to reproduce this behavior with your vite stackblitz template linked above.

https://stackblitz.com/edit/github-8swqiz1q?file=src%2Fapp.tsx

This is the segment that is relevant:

import Markdown from 'react-markdown';
import rehypeRaw from 'rehype-raw';

const markdown = '<br/>\n[test](https://example.com)';

function App() {
  return <Markdown rehypePlugins={[rehypeRaw]}>{markdown}</Markdown>;
}

It displays the following (including the newline):

[test](https://example.com)

For now, I simply replace the <br/>\n at the start of the string with a simple <br/> which fixes the issue, but I would like have a proper solution to this. Am I misunderstanding some markdown spec or is this an issue of the library?

I tried this exact string with several other local and online renderers and none of these showed this behavior.

Actual behavior

The rendered content is:

[test](https://example.com)

Expected behavior

I would expect the content to be:

<a href="https://example.com">test</a>

(or something related).

Runtime

Firefox 142.0.1 (64-bit)

Package manager

npm@10.8.2 on your stackblitz and npm@6.14.13 locally

Operating system

macOS 15.4.1 (24E263)

Build and bundle tools

CRA (Create React App), Vite

[wooorm]

Hi! Right, that’s how markdown works.

<br>
[test](https://example.com/)

Yields:

[test](https://example.com/)

See also: https://spec.commonmark.org/dingus/?text=%3Cbr%3E%0A%5Btest%5D(https%3A%2F%2Fexample.com)%0A

[github-actions]

Hi! This was closed. Team: If this was fixed, please add phase/solved. Otherwise, please add one of the no/* labels.