Extending `react-app` eslint config in non-typescript app

[thisismydesign]

Describe the bug

I'm trying the DISABLE_ESLINT_PLUGIN flag added to react-scripts in v4.0.2. In .eslintrc.js:

  extends: [
    "react-app",
  ]

This gives me

$ eslint .

Oops! Something went wrong! :(

ESLint: 7.19.0

Error: Failed to load parser '@typescript-eslint/parser' declared in '.eslintrc.js » eslint-config-react-app#overrides[0]': Cannot find module 'typescript'

I'm on a non-typescript project. Do I still have to configure it as if it was a typescript project if I want to use the react-app ruleset? This is what the readme of https://www.npmjs.com/package/eslint-config-react-app indicates as well, but it would be great to be able to use it without all of these dependencies. Especially when using create-react-app.

Environment

Environment Info:

  current version of create-react-app: 4.0.2
  running from /root/.npm/_npx/13859/lib/node_modules/create-react-app

  System:
    OS: Linux 4.19 Ubuntu 18.04.1 LTS (Bionic Beaver)
    CPU: (4) x64 Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz
  Binaries:
    Node: 14.10.0 - ~/.nvm/versions/node/v14.10.0/bin/node
    Yarn: 1.22.5 - ~/.nvm/versions/node/v14.10.0/bin/yarn
    npm: 6.14.8 - ~/.nvm/versions/node/v14.10.0/bin/npm
  Browsers:
    Chrome: Not Found
    Firefox: Not Found
  npmPackages:
    react: ^16.13.1 => 16.13.1 
    react-dom: ^16.13.1 => 16.13.1 
    react-scripts: 4.0.2 => 4.0.2 
  npmGlobalPackages:
    create-react-app: Not Found

[mrmckeb]

Hi @thisismydesign, this has been an issue for a long time now I think.

It's because we use TS dependencies in the config, even if those are scoped to .ts and .tsx files.
https://github.com/facebook/create-react-app/blob/master/packages/eslint-config-react-app/index.js#L34

I'm not 100% sure how to solve this - we have the same problem with an ESLint config in my company, but ignored it as we only use TS on new projects anyway... So I get that it can be a pain-point.

Do you have any thoughts on this? Maybe @ianschmitz has some ideas too.