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) {
        config.module.rules[4].use.splice(1, 0, {
            loader: "@teamsupercell/typings-for-css-modules-loader",
            options: {
                banner:
                    "// This file is automatically generated from your CSS. Any edits will be overwritten.",
                disableLocalsExport: true
            }
        });

        // Use any `index` file, not just index.js
        config.resolve.alias["preact-cli-entrypoint"] = resolve(
            process.cwd(),
            "src",
            "index"
        );
    }
};