respect wepack export condition for importing

[spike-rabbit]

Command

build, extract-i18n, serve, test

Description

The root problem I am trying to solve is the different import behavior of esbuild and webpack for url resources like described here ( https://github.com/angular/angular-cli/issues/24470 ).

We have a npm package shipping company fonts and scss file to import them.

I know that there are other possibilities, but I also discovered that we could have different entrypoints for webpack and esbuild when using conditions in the package.json as described here: https://webpack.js.org/guides/package-exports/#conditions-preprocessor-and-runtimes.

This was leading me to this package.json

  "exports": {
    "./styles/*": {
      "webpack": {
        "sass": "./dist/styles/webpack/*.scss",
        "less": "./dist/styles/webpack/*.less",
        "style": "./dist/styles/webpack/*.css"
      },
      "sass": "./dist/styles/*.scss",
      "less": "./dist/styles/*.less",
      "style": "./dist/styles/*.css"
    },
    "./*": "./dist/fonts/*"
  }

The only problem here is, that this does not work. Webpack is loading the normal sass styles.

Describe the solution you'd like

It would be really cool if the webpack condition is matched.

Describe alternatives you've considered

We could offer a scss variable so that consumers can override the font path or just casually export the file. This still does not solve the problem when using esbuild and the karma runner but at least they could do something.

I am not sure how much effort it is fixing this, but in case you just need to add webpack here: https://github.com/angular/angular-cli/blob/main/packages/angular_devkit/build_angular/src/tools/webpack/configs/styles.ts#L382 it would be really cool if you could do it.

[dgp1130]

We do expect some amount of breaking changes between browser and application builders, so supporting library authors exporting different files for the different build systems does make some amount of sense. I wish we didn't have to do that, but for library authors to support both it might be necessary.

Ideally we'd just have the same behavior for both build systems, and maybe we can improve the story for https://github.com/angular/angular-cli/issues/24470, but even if we do, it feels like there will be other subtle breaking changes which can cause pain for library authors. If we're expecting some amount of those breaking changes with no common format that works for both, then we might need something like this to support libraries trying to be compatible with both build systems.

@clydin, what do you think about this?

[angular-robot[bot]]

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