react19-source-patterns

ReactDOM.render(...)

→ createRoot().render()

See references/api-migrations.md

ReactDOM.hydrate(...)

→ hydrateRoot(...)

See references/api-migrations.md

unmountComponentAtNode

→ root.unmount()

Keep the root returned by createRoot or hydrateRoot so unmount can be called on it. See references/api-migrations.md

ReactDOM.findDOMNode

→ direct ref

Attach a ref to the specific DOM element, passing ref as a prop for function children, and flag unclear targets for manual review. See references/api-migrations.md

forwardRef(...) wrapper

→ ref as direct prop

See references/api-migrations.md

Component.defaultProps = {} on function components

→ ES6 default params. Class components still support defaultProps in React 19, so keep them as written

See references/api-migrations.md

useRef() no arg

→ useRef(null)

Inline fix: add null for DOM element refs. For refs that hold values rather than elements, keep the existing undefined behavior if code checks for undefined

Legacy Context

→ createContext

Legacy Context API Removed section in references/api-migrations.md

String refs this.refs.x

→ createRef()

String Refs Removed section in references/api-migrations.md

import React from 'react' (unused)

Remove

Only if no React. usage in file and the build config uses the automatic JSX runtime. Keep it in JSX files under the classic runtime