add —use-npm flag to bypass yarn

[tabrindle]

Allow user to choose npm over yarn. This should close #3385.

[bondz]

Yes, this should work. We can add a test for this in the e2e tests though. Checking if a yarn.lock does not exist when this flag is specified should be sufficient, right?

[tabrindle]

Yeah that's a great idea. Will add.

[react-scripts-dangerous]

Hello! I'm a bot that helps facilitate testing pull requests.

Your pull request (commit 547ad01) has been released on npm for testing purposes.

npm i react-scripts-dangerous@1.0.17-547ad01.0
# or
yarn add react-scripts-dangerous@1.0.17-547ad01.0
# or
create-react-app --scripts-version=react-scripts-dangerous@1.0.17-547ad01.0 folder/

Note that the package has not been reviewed or vetted by the maintainers. Only install it at your own risk!

Thanks for your contribution!

[bondz]

I don't think we need to install a specific version here.

This looks good to go. 👍

[Timer]

Shouldn't hurt 😄

[Timer]

Thanks!

[SimenB]

This option should be documented, ref jestjs/jest#5119 (comment)

[corysimmons]

Should probably be documented, but tbh, I'm trash for not create-react-app --help and spotting it.

gaearon said something about not wanting to add flags a while back (albeit, in reference to adding a --bare option in favor of adding a more flexible --template option) so I just blindly assumed CRA didn't have flags. 😅

[AmitJoki]

What's the preferred way of using this flag on an existing project? I already have a CRA but I am wanting to opt out from yarn. How do I go about?

[bondz]

@AmitJoki Delete your yarn.lock file and run npm i and then continue to use npm commands thereafter.