react-devtools-core

This package provides low-level APIs to support renderers like React Native. If you're looking for the standalone React DevTools UI, we suggest using react-devtools instead of using this package directly.

This package provides two entrypoints: labeled "backend" and "standalone" (frontend). Both APIs are described below.

Backend API

Backend APIs are embedded in development builds of renderers like React Native in order to connect to the React DevTools UI.

Example

If you are building a non-browser-based React renderer, you can use the backend API like so:

if (process.env.NODE_ENV !== 'production') {
  const { initialize, connectToDevTools } = require("react-devtools-core");

  initialize(settings);
  // Must be called before packages like react or react-native are imported
  connectToDevTools({...config});
}

NOTE that this API (connectToDevTools) must be (1) run in the same context as React and (2) must be called before React packages are imported (e.g. react, react-dom, react-native).

initialize arguments

Settings

Component filters

Each filter object must include type and isEnabled. Some filters also require value or isValid.

connectToDevTools options

connectWithCustomMessagingProtocol options

Unlike connectToDevTools, connectWithCustomMessagingProtocol returns a callback, which can be used for unsubscribing the backend from the global DevTools hook.

Frontend API

Frontend APIs can be used to render the DevTools UI into a DOM node. One example of this is react-devtools which wraps DevTools in an Electron app.

Example

import DevtoolsUI from "react-devtools-core/standalone";

// See the full list of API methods in documentation below.
const { setContentDOMNode, startServer } = DevtoolsUI;

// Render DevTools UI into a DOM element.
setContentDOMNode(document.getElementById("container"));

// Start socket server used to communicate between backend and frontend.
startServer(
  // Port defaults to 8097
  1234,

  // Host defaults to "localhost"
  "example.devserver.com",

  // Optional config for secure socket (WSS).
  {
    key: fs.readFileSync('test/fixtures/keys/agent2-key.pem'),
    cert: fs.readFileSync('test/fixtures/keys/agent2-cert.pem')
  }
);

Exported methods

The default export is an object defining the methods described below.

These methods support chaining for convenience. For example:

const DevtoolsUI = require("react-devtools-core/standalone");
DevtoolsUI.setContentDOMNode(element).startServer();

connectToSocket(socket: WebSocket)

This is an advanced config function that is typically not used.

Custom WebSocket connection to use for communication between DevTools frontend and backend. Calling this method automatically initializes the DevTools UI (similar to calling startServer()).

openProfiler()

Automatically select the "Profiler" tab in the DevTools UI.

setContentDOMNode(element: HTMLElement)

Set the DOM element DevTools UI should be rendered into on initialization.

setDisconnectedCallback(callback: Function)

Optional callback to be notified when DevTools WebSocket closes (or errors).

setProjectRoots(roots: Array<string>)

Optional set of root directories for source files. These roots can be used to open an inspected component's source code using an IDE.

setStatusListener(callback: Function)

Optional callback to be notified of socket server events (e.g. initialized, errored, connected).

This callback receives two parameters:

function onStatus(
  message: string,
  status: 'server-connected' | 'devtools-connected' | 'error'
): void {
  // ...
}

startServer(port?, host?, httpsOptions?, loggerOptions?, path?, clientOptions?)

Start a socket server (used to communicate between backend and frontend) and renders the DevTools UI.

This method accepts the following parameters:

clientOptions

When connecting through a reverse proxy, the client may need to connect to a different host, port, or protocol than the local server. Use clientOptions to override what appears in the connectToDevTools() script served to clients. Any field not set falls back to the corresponding server value.

These can also be set via environment variables in the Electron app:

Reverse proxy example

Run DevTools locally on the default port, but tell clients to connect through a remote proxy:

REACT_DEVTOOLS_CLIENT_HOST=remote.example.com \
REACT_DEVTOOLS_CLIENT_PORT=443 \
REACT_DEVTOOLS_CLIENT_USE_HTTPS=true \
REACT_DEVTOOLS_PATH=/__react_devtools__/ \
react-devtools

The server listens on localhost:8097. The served script tells clients:

connectToDevTools({host: 'remote.example.com', port: 443, useHttps: true, path: '/__react_devtools__/'})

Development

Watch for changes made to the backend entry point and rebuild:

yarn start:backend

Watch for changes made to the standalone UI entry point and rebuild:

yarn start:standalone

Run the standalone UI using yarn start in the react-devtools.

Source: packages/react-devtools-core/README.md