bryik/cra-web-workers

Demonstrates how to have web workers in a create-react-app project.

cra-web-workers

This is a demonstration of using worker-loader to run a web worker in a create-react-app project.

See this issue thread and this article for more details.

why is this useful?

create-react-app does not currently support web workers (the Webpack config is not setup for it or something). However, worker-loader can be inlined (side-stepping the need to eject from CRA).

how does it work?

Tracing a click of the increment button:

1. The increment button is clicked causing the onClick handler to be called.
2. The onClick handler calls worker.postMessage() with an object describing what the worker should do: { type: "increment" }.
3. The worker, in its separate thread, receives the message which triggers the onmessage() handler. The onmessage() handler looks at { type: "increment" } and determines that the increment() function should be called. After increment() is called, the worker calls postMessage() to inform the main thread of the new count: { type: "update", count }.
4. The main thread receives the message in the newWorker.onmessage() handler, interprets it, and finally calls setCount() which updates the component's local state.
5. <Counter /> is re-rendered, the new count is displayed.

It is silly to offload quick calculations like this to a worker, but this is just a demo.

Available Scripts

In the project directory, you can run:

npm start

Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

npm test

Launches the test runner in the interactive watch mode.
See the section about running tests for more information.

npm run build

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

See the section about deployment for more information.

npm run eject

Note: this is a one-way operation. Once you eject, you can’t go back!

If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.

Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.

You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.

Learn More

You can learn more in the Create React App documentation.

To learn React, check out the React documentation.

Code Splitting

This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting

Analyzing the Bundle Size

This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size

Making a Progressive Web App

This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app

Advanced Configuration

This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration

Deployment

This section has moved here: https://facebook.github.io/create-react-app/docs/deployment

npm run build fails to minify

This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify