preact.config.js

import { resolve } from "path";

export default {
    /**
     * Function that mutates the original webpack config.
     * Supports asynchronous changes when a promise is returned (or it's an async function).
     *
     * @param {object} config - original webpack config.
     * @param {object} env - options passed to the CLI.
     * @param {WebpackConfigHelpers} helpers - object with useful helpers for working with the webpack config.
     * @param {object} options - this is mainly relevant for plugins (will always be empty in the config), default to an empty object
     **/
    webpack(config, env, helpers, options) {
        // Switch css-loader for typings-for-css-modules-loader, which is a wrapper
        // that automatically generates .d.ts files for loaded CSS
        helpers.getLoadersByName(config, "css-loader").forEach(({ loader }) => {
            loader.loader = "typings-for-css-modules-loader";
            loader.options = Object.assign(loader.options, {
                camelCase: true,
                banner:
                    "// This file is automatically generated from your CSS. Any edits will be overwritten.",
                namedExport: true,
                silent: true
            });
        });
    }
};