experimental-loader

Experimental Stylable Webpack Loader

This loader supports working with mini-css-extract-plugin. Internally, this setup uses two separate loaders.

• stylable-transform-loader - responsible for Stylable transformations and generates the css-loader compatible output that the mini-css-extract-plugin expects
• stylable-runtime-loader - Stylable offers a richer module API compared to css modules. The css-loader flow does not support this API, and so we are using this loader to convert the raw Stylable locals data to the appropriate runtime stylesheet

Disclaimer

This loader is experimental and currently not the recommended way of integrating Stylable into your project.
Use @stylable/webpack-plugin for the latest stable integration.

• native css import is not supported

Example

A minimal webpack configuration using the two Stylable loaders in conjunction with the mini-css-extract-plugin loader:

const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const { stylableLoaders } = require('@stylable/experimental-loader');

module.exports = {
  plugins: [new MiniCssExtractPlugin()],
  module: {
    rules: [
      {
        test: /\.st\.css$/i,
        use: [
          stylableLoaders.runtime(),
          MiniCssExtractPlugin.loader,
          stylableLoaders.transform(),
        ],
      },
      // load asset from CSS url()
      {
        test: /\.(png|jpg|gif)$/i,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 8192,
            },
          },
        ],
      },
    ],
  },
};

Transform loader options

interface LoaderOptions {
  resolveNamespace?(namespace: string, filePath: string): string;
  filterUrls?(url: string, ctx: loader.LoaderContext): boolean;
  exportsOnly?: boolean;
  alwaysEmitErrors?: boolean;
}

Option	Description
resolveNamespace	override default stylesheet namespace process
filterUrls	filter urls from webpack process
exportsOnly	only export the runtime stylesheet
alwaysEmitErrors	always emit Stylable diagnostics as errors

SSR (exportsOnly)

When building Stylable for consumption in a server-side renderer build, you may want to extract only the exports of the runtime stylesheets and not the content of their CSS. In such a case you would only be required to use the transform loader and the exportsOnly option.

{
  test: /\.st\.css$/i,
  use: [
    stylableLoaders.transform({ exportsOnly: true }),
  ],
}

Known issues

As opposed to the current webpack-plugin integration, some behaviors are still missing, or lacking:

• The loader does not perform Stylable specific optimizations such as: minimizing namespaces and classNames, removing unused rules, and so on
• May encounter issues with CSS loading order (order being determined by JS imports) - webpack open issue
• May have issues with updating CSS when JS imports change order in dev time watch mode

License

Copyright (c) 2021 Wix.com Ltd. All Rights Reserved. Use of this source code is governed by a MIT license.