eslint-plugin-react-19-upgrade

An ESLint plugin to identify and fix breaking changes when upgrading React 18 to React 19

Installation

You'll first need to install ESLint:

$ npm install eslint --save-dev

Next, install eslint-plugin-react-19-upgrade:

$ npm install eslint-plugin-react-19-upgrade --save-dev

Usage

Add react-19-upgrade to the plugins section of your .eslintrc or equivalent configuration file. You can omit the eslint-plugin- prefix:

{
  "plugins": ["react-19-upgrade"]
}

Then configure the rules you want to use under the rules section.

{
  "rules": {
    "react-19-upgrade/no-default-props": "error",
    "react-19-upgrade/no-prop-types": "warn",
    "react-19-upgrade/no-legacy-context": "error",
    "react-19-upgrade/no-string-refs": "error",
    "react-19-upgrade/no-factories": "error",
    "react-19-upgrade/no-legacy-react-dom": "error",
    "react-19-upgrade/no-legacy-react-dom-server": "error",
    "react-19-upgrade/no-legacy-test-utils": "error",
    "react-19-upgrade/no-legacy-react-is": "error",
    "react-19-upgrade/no-shallow-renderer": "error",
    "react-19-upgrade/no-implicit-ref-callback-return": "error"
  }
}

Supported Rules

• no-default-props: Move defaultProps to default parameters in the destructured props. Fixable by ESLint.
• no-prop-types: Avoid using propTypes as they are now ignored in React 19.
• no-legacy-context: Disallow the use of legacy context APIs in React class components.
• no-string-refs: Disallow the use of string refs in React components.
• no-factories: Disallow module pattern factories and React.createFactory.
• no-legacy-react-dom: Disallow removed react-dom APIs (render, hydrate, unmountComponentAtNode, findDOMNode, plus the removed unstable_flushControlled, unstable_createEventHandle, renderSubtreeIntoContainer/unstable_renderSubtreeIntoContainer, and unstable_runWithPriority). Use createRoot/hydrateRoot from react-dom/client, or refs, instead.
• no-legacy-react-dom-server: Disallow renderToNodeStream and renderToStaticNodeStream from react-dom/server. Use renderToPipeableStream instead (note: different signature).
• no-legacy-test-utils: Disallow importing from react-dom/test-utils, which is removed entirely in React 19. act imports are rewritten to import from react (Fixable by ESLint); the other utilities (Simulate, renderIntoDocument, etc.) are reported with a pointer to @testing-library/react. Supersedes no-legacy-test-utils-act — enable one or the other, not both.
• no-legacy-test-utils-act: Import act from react, not react-dom/test-utils. Fixable by ESLint. Narrower than no-legacy-test-utils (only flags act); kept for backwards compatibility.
• no-legacy-react-is: Disallow isConcurrentMode and isAsyncMode from react-is, removed in React 19 without a replacement.
• no-shallow-renderer: Disallow importing react-test-renderer/shallow, removed in React 19. Rewritten to react-shallow-renderer (install it first). Fixable by ESLint.
• no-implicit-ref-callback-return: Disallow implicit returns in JSX ref callbacks (ref={el => (this.el = el)}) — React 19 treats the returned value as a cleanup function. The body is wrapped in braces (Fixable by ESLint). Only arrow expression bodies are flagged, matching the official react/19 codemod; explicit return statements and function-expression refs are left alone.

element.ref access

React 19 makes ref a regular prop, so element.ref becomes element.props.ref. This plugin does not lint for it — any sound static heuristic either misses real cases or produces false positives on valid code. Use the official React codemod instead: npx codemod@latest react/19/replace-ref-access.