npm start​

Runs the app in the development mode. Openhttp://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 aboutrunning tests for more information.

npm run build​

Builds the app for production to thebuild 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. If necessary, classnames and function names can be enabled for profiling purposes. See theproduction build section for more information.

Your app is ready to be deployed! See the section aboutdeployment for more information about deploying your application to popular hosting providers.

npm run eject​

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

If you aren’t satisfied with the build tool and configuration choices, you caneject 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.) into your project as dependencies inpackage.json. Technically, the distinction between dependencies and development dependencies is pretty arbitrary for front-end apps that produce static bundles.

In addition, it used to cause problems with some hosting platforms that didn't install development dependencies (and thus weren't able to build the project on the server or test it right before deployment). You are free to rearrange your dependencies inpackage.json as you see fit.

All of the commands excepteject 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 useeject. 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.