Move TypeScript dependencies out of createReactApp.js

[zachwolf]

Is your proposal related to a problem?

The npm ecosystem has the expectation that package.json contains information for its package. Currently, when updating dependencies, it's one more thing to remember when TypeScript dependencies are maintained inside of createReactApp.js. This makes tools like npm outdated not able to find these dependencies.

Describe the solution you'd like

What has worked well for my team's project, is to add another package that can maintain and export its own dependencies. For example:

 📂 create-react-app
  ├ 📁 babel-plugin-named-asset-import
  ├ 📁 babel-preset-react-app
  ├ 📁 confusing-browser-globals
  ├ 📁 cra-template-typescript
  ├ 📁 cra-template
  ├ 📁 create-react-app
  ├ 📁 eslint-config-react-app
  ├ 📁 react-app-polyfill
  ├ 📁 react-dev-utils
  ├ 📁 react-error-overlay
  ├ 📁 react-scripts
+ └ 📂 typescript-dependencies
+   ├ 📂 index.js      # reads package.json and exports values
+   └ 📂 package.json  # define dependencies

Then, in createReactApp.js:

if (!supportsTemplates && (template || '').includes('typescript')) {
-  allDependencies.push(
-    '@types/node',
-    '@types/react',
-    '@types/react-dom',
-    '@types/jest',
-    'typescript'
-  );
+  const typeScriptDependencies = require('typescript-dependencies')()
+  allDependencies = allDependencies.concat(typeScriptDependencies)
}

Describe alternatives you've considered

I'm missing context around create-react-app's roadmap. Forgive me if this issue is already solved with the recent and upcoming changes around how templates are maintained. I see that cra-template-typescript/template.json might have already solved the problem. However, the TypeScript dependency check is still in place in createReactApp.js.

[heyimalex]

I don’t understand how npm outdated can’t find the dependencies? I’m pretty sure they end up in the root package.json, not nested inside of react-scripts or anything like that.

[ianschmitz]

You're correct, they do @heyimalex. I'm not quite following the OP. These dependencies are controlled by the developer within their application.

[zachwolf]

Ahh, sorry, let me clarify.

When running npm outdated inside of create-react-app's monorepo, the dependencies are not discoverable. E.g.:

$ cd create-react-app
$ lerna exec npm outdated

I'm using npm outdated only an example. My intention isn't to focus on that functionality specifically.

My end goal is for CRA contributors to be able to use the tools built for the JavaScript ecosystem.

[zachwolf]

No longer an issue with 3.3.0 🤠