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react-devtools

react-devtools

If you need to debug a React page somewhere other than Chrome on desktop (a mobile browser, an embedded webview, Safari, etc), the react-devtools package is for you! It is also useful if your app is inside an iframe.

It works both with React DOM and React Native.

Screenshot of React DevTools running with React Native

Usage with React Native

Install the react-devtools package globally:

npm install -g react-devtools

Now run react-devtools from the terminal to launch the standalone DevTools app:

react-devtools

If you're using React Native 0.43 or higher, it should connect to your simulator within a few seconds.

Note: if you prefer to avoid global installations, you can add react-devtools as a project dependency. With Yarn, you can run yarn add --dev react-devtools, and then run yarn react-devtools from your project folder to open the DevTools. With npm, you can run npm install --save-dev react-devtools, add "react-devtools": "react-devtools" to the scripts section in your package.json, and then run npm run react-devtools from your project folder to open the DevTools.

Integration with React Native Inspector

You can open the in-app developer menu and choose "Show Inspector". It will bring up an overlay that lets you tap on any UI element and see information about it:

React Native Inspector

However, when react-devtools is running, Inspector will enter a special collapsed mode, and instead use the DevTools as primary UI. In this mode, clicking on something in the simulator will bring up the relevant components in the DevTools:

React DevTools Inspector Integration

You can choose "Hide Inspector" in the same menu to exit this mode.

Inspecting Component Instances

When debugging JavaScript in Chrome, you can inspect the props and state of the React components in the browser console.

First, follow the instructions for debugging in Chrome to open the Chrome console.

Make sure that the dropdown in the top left corner of the Chrome console says debuggerWorker.js. This step is essential.

Then select a React component in React DevTools. There is a search box at the top that helps you find one by name. As soon as you select it, it will be available as $r in the Chrome console, letting you inspect its props, state, and instance properties.

React DevTools Chrome Console Integration

Usage with React DOM

The standalone shell can also be useful with React DOM (for example, to debug apps in Safari, or inside an iframe).

Install the react-devtools package globally:

npm install -g react-devtools

Now run react-devtools from the terminal to launch the standalone DevTools app:

react-devtools

Finally, add <script src="http://localhost:8097"></script> as the very first <script> tag in the <head> of your page when developing:

<!doctype html>
<html lang="en">
  <head>
    <script src="http://localhost:8097"></script> 

This will ensure the developer tools are connected.
Don’t forget to remove it before deploying to production!

Note: if you prefer to avoid global installations, you can add react-devtools as a project dependency. With Yarn, you can run yarn add --dev react-devtools, and then run yarn react-devtools from your project folder to open the DevTools. With npm, you can run npm install --save-dev react-devtools, add "react-devtools": "react-devtools" to the scripts section in your package.json, and then run npm run react-devtools from your project folder to open the DevTools.

If you install react-devtools as a project dependency, you may also replace the <script> suggested above with a JavaScript import (import 'react-devtools'). It is important that this import comes before any other imports in your app (especially before react-dom). Make sure to remove the import before deploying to production, as it carries a large DevTools client with it. If you use Webpack and have control over its configuration, you could alternatively add 'react-devtools' as the first item in the entry array of the development-only configuration, and then you wouldn’t need to deal either with <script> tags or import statements.

Advanced

By default DevTools listen to port 8097 on localhost.
If you need to customize host, port, or other settings, see the react-devtools-core package instead.

Developing

  • Run npm run backend:watch and npm run standalone:watch in ../react-devtools-core
  • Run npm start in this folder
  • Refresh the app after it has recompiled on change
  • For React Native, copy react-devtools-core to its node_modules to test your changes