@react-native/dev-middleware
Advanced tools
Dev server middleware supporting core React Native development features. This package is preconfigured in all React Native projects.
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
},
});
}
@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:
DevMiddlewareAPI.middleware
These are exposed as a connect middleware handler, assignable to Metro.runServer or other compatible HTTP servers.
/json/list, /json (CDP)Returns the list of available WebSocket targets for all connected React Native app sessions.
/json/version (CDP)Returns version metadata used by Chrome DevTools.
/debugger-frontendSubpaths of this endpoint are reserved to serve the JavaScript debugger frontend.
/open-debuggerOpen the JavaScript debugger for a given CDP target (direct Hermes debugging).
curl -X POST 'http://localhost:8081/open-debugger?appId=com.meta.RNTester'
DevMiddlewareAPI.websocketEndpoints
/inspector/deviceWebSocket handler for registering device connections.
/inspector/debugWebSocket handler that proxies CDP messages to/from the corresponding device.
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.
v0.76.9
FAQs
Dev server middleware for React Native
The npm package @react-native/dev-middleware receives a total of 2,133,168 weekly downloads. As such, @react-native/dev-middleware popularity was classified as popular.
We found that @react-native/dev-middleware demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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