Cedric van Putten
652c74104a
Summary: This is a follow-up bugfix for expo/expo#27425, related to: - https://github.com/facebook/react-native/issues/43291 - https://github.com/facebook/react-native/issues/43307 - https://github.com/facebook/react-native/issues/43310 - https://github.com/facebook/react-native/issues/43364 The middleware API works as intended and can run our extended CDP events. Unfortunately, this only applies to an actual `Page` from the device, not for the `React Native Experimental (Improved Chrome Reloads)` synthetic / virtual page. That's because the middleware instantiation gets aborted when the page can't be found in `this.#pages.get(pageId)`, which always returns `null` for this synthetic page. ## Changelog: [GENERAL] [FIXED] Create custom message handler for synthetic page Pull Request resolved: https://github.com/facebook/react-native/pull/43559 Test Plan: See added test case. Reviewed By: motiz88 Differential Revision: D55129412 Pulled By: huntie fbshipit-source-id: 9679d8fe68f3cb4104f4a042f93612b995baddc9
@react-native/dev-middleware
Dev server middleware supporting core React Native development features. This package is preconfigured in all React Native projects.
Usage
Middleware can be attached to a dev server (e.g. Metro) using the createDevMiddleware API.
import { createDevMiddleware } from '@react-native/dev-middleware';
function myDevServerImpl(args) {
...
const {middleware, websocketEndpoints} = createDevMiddleware({
projectRoot: metroConfig.projectRoot,
serverBaseUrl: `http://${args.host}:${args.port}`,
logger,
});
await Metro.runServer(metroConfig, {
host: args.host,
...,
unstable_extraMiddleware: [
middleware,
// Optionally extend with additional HTTP middleware
],
websocketEndpoints: {
...websocketEndpoints,
// Optionally extend with additional WebSocket endpoints
},
});
}
Included middleware
@react-native/dev-middleware is designed for integrators such as @expo/dev-server and @react-native/community-cli-plugin. It provides a common default implementation for core React Native dev server responsibilities.
We intend to keep this to a narrow set of functionality, based around:
- Debugging — The Chrome DevTools protocol (CDP) endpoints supported by React Native, including the Inspector Proxy, which facilitates connections with multiple devices.
- Dev actions — Endpoints implementing core Dev Menu actions, e.g. reloading the app, opening the debugger frontend.
HTTP endpoints
DevMiddlewareAPI.middleware
These are exposed as a connect middleware handler, assignable to Metro.runServer or other compatible HTTP servers.
GET /json/list, /json (CDP)
Returns the list of available WebSocket targets for all connected React Native app sessions.
GET /json/version (CDP)
Returns version metadata used by Chrome DevTools.
GET /debugger-frontend
Subpaths of this endpoint are reserved to serve the JavaScript debugger frontend.
POST /open-debugger
Open the JavaScript debugger for a given CDP target (direct Hermes debugging).
Example
curl -X POST 'http://localhost:8081/open-debugger?appId=com.meta.RNTester'
WebSocket endpoints
DevMiddlewareAPI.websocketEndpoints
/inspector/device
WebSocket handler for registering device connections.
/inspector/debug
WebSocket handler that proxies CDP messages to/from the corresponding device.
Contributing
Changes to this package can be made locally and tested against the rn-tester app, per the Contributing guide. During development, this package is automatically run from source with no build step.