boshi-xixixi / react19-source-patterns

Name: boshi-xixixi/react19-source-patterns
Author: boshi-xixixi

Reference for React 19 source-file migration patterns, including API changes, ref handling, and context updates.

Version

SKILL.md

1.9 KB

React 19 Source Migration Patterns

Reference for every source-file migration required for React 19.

Quick Reference Table

Pattern	Action	Reference
`ReactDOM.render(...)`	→ `createRoot().render()`	See references/api-migrations.md
`ReactDOM.hydrate(...)`	→ `hydrateRoot(...)`	See references/api-migrations.md
`unmountComponentAtNode`	→ `root.unmount()`	Inline fix
`ReactDOM.findDOMNode`	→ direct ref	Inline fix
`forwardRef(...)` wrapper	→ ref as direct prop	See references/api-migrations.md
`Component.defaultProps = {}`	→ ES6 default params	See references/api-migrations.md
`useRef()` no arg	→ `useRef(null)`	Inline fix add `null`
Legacy Context	→ `createContext`	[→ api-migrations.md#legacy-context](references/api-migrations.md#legacy-context)
String refs `this.refs.x`	→ `createRef()`	[→ api-migrations.md#string-refs](references/api-migrations.md#string-refs)
`import React from 'react'` (unused)	Remove	Only if no `React.` usage in file

PropTypes Rule

Do not remove .propTypes assignments. The prop-types package still works as a standalone validator. React 19 only removes the built-in runtime checking from the React package the package itself remains valid.

Add this comment above any .propTypes block:

// NOTE: React 19 no longer runs propTypes validation at runtime.
// PropTypes kept for documentation and IDE tooling only.

Read the Reference

For full before/after code for each migration, read references/api-migrations.md. It contains the complete patterns including edge cases for forwardRef with useImperativeHandle, defaultProps null vs undefined behavior, and legacy context provider/consumer cross-file migrations.