npx create-react-app@next --scripts-version=@next --template=cra-template@next my-js-app
npx create-react-app@next --scripts-version=@next --template=typescript@next my-ts-app
To update an existing app you can change the react-scripts
version in package.json
to next
and then run yarn
or npm install
You can see a list of all the changes in the 4.0 release here
I've been getting some similar npm errors in the last few minutes on unrelated projects. I think they might be having an issue. Rerunning yarn or npm seems to have fixed it for me. Hopefully this is just a temporary problem.