Bug: `<link rel="preload" as="font" ...>` in RSC gets duplicated in SSR html | GoodFirstPicks

Bug: `<link rel="preload" as="font" ...>` in RSC gets duplicated in SSR html

facebook/react 0 comments 1mo ago

mediumopenScope: somewhat clearSkill match: maybeTest focusedReactJavaScriptTypeScript

Why this is a good first issue

The issue involves SSR-specific behavior and requires understanding React internals.

AI Summary

The issue involves `<link rel='preload' as='font' ...>` being duplicated in SSR HTML, which started occurring from React 19.2.0. A test case has been provided in a PR, but the fix likely requires understanding React's SSR handling and internal mechanisms. The scope is somewhat clear, but the implementation may involve deeper React internals.

Issue Description

React version: since 19.2.0

Steps To Reproduce

Created a PR with a test case as a reproduction in https://github.com/facebook/react/pull/35890

Initially reported on Waku https://github.com/wakujs/waku/issues/1964#issuecomment-3948147703. It doesn't reproduce on 19.1. It reproduces from 19.2 and latest canary.

The current behavior

<link rel="preload" as="font" ... /> appears twice in SSR html

The expected behavior

<link rel="preload" as="font" .../> appears once in SSR html

GitHub Labels

Status: UnconfirmedComponent: Server Rendering

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Risk Flags

potential SSR-specific behavior
requires understanding of React internals

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Details

Points20 pts

Difficultymedium

Scopesomewhat clear

Skill Matchmaybe

Test Focusedyes