Remove dependency on babel

[kumikumi]

I have created some projects using create-react-app-typescipt, and would like to get rid of babel as a dependency.

From #394 I have understood that babel is not (meant to be?) used in this project at all. However, this package seems to have dependencies on "babel-jest", "babel-loader" and "babel-preset-react-app", which cause "babel-core" and all its subdependencies to be included. I understand that babel is an ES2015+ transpiler and should therefore have no real use in a pure TypeScript project, or having a dependency on it should at most be optional.

I did a quick experiment to see if babel is really required, and turns out you can indeed create a new react app and get away with removing almost all babel-related packages (by hand) from node_modules and keep a working setup.

For some reason npm start command still requires these 4 babel modules to be present:

babel-code-frame
babel-loader
babel-preset-react-app
babel-runtime

npm run test probably requires more.

What is going on here?

[DorianGrey]

The statement you mentioned isn't an official one, and it's ... wrong.
Just take a look at the webpack configurations ...
E.g.:

create-react-app-typescript/config/webpack.config.dev.js

Lines 160 to 169 in eb34688

	test: /\.(js|jsx|mjs)$/,
	include: paths.appSrc,
	loader: require.resolve('babel-loader'),
	options: {
	// @remove-on-eject-begin
	babelrc: false,
	presets: [require.resolve('babel-preset-react-app')],
	// @remove-on-eject-end
	compact: true,
	},

It's still allowed to import and use js files, which might be quite common during migrations. At least there were quite a lot of requests for this. Since require.resolve is used to avoid clunky webpack message when a loader could not be found, it is enforced that these packages are present - they are resolved before the build.
babel-code-frame is used by the type checker to generate a code frame for each reported error.
babel-jest is referenced by jest by default, and thus cannot be omitted.

[danielkcz]

Isn't TypeScript capable of transforming JavaScript as well? It's just a file without types, so it shouldn't be a problem, right?

That said, if we would remove Babel completely, we would close the path for babel-plugin-macros which is extremely handy and used by more and more projects now and included in CRA2. However, in the and it means that we need to use babel-loader for TypeScript files as well.