webpack.config.js

const Encore = require('@symfony/webpack-encore');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const path = require("path");

// Manually configure the runtime environment if not already configured yet by the "encore" command.
// It's useful when you use tools that rely on webpack.config.js file.
if (!Encore.isRuntimeEnvironmentConfigured()) {
    Encore.configureRuntimeEnvironment(process.env.NODE_ENV || 'dev');
}

Encore
    // directory where compiled assets will be stored
    .setOutputPath('public/build/')
    // public path used by the web server to access the output path
    .setPublicPath('/build')
    // only needed for CDN's or sub-directory deploy
    //.setManifestKeyPrefix('build/')
    .addPlugin(new HtmlWebpackPlugin ({
        template: 'src/inline.html',
        filename: '../inline.html',
        chunks: ['layout'],
        inject: "body"
    }))
    .addPlugin(new HtmlWebpackPlugin ({
        template: 'src/external.html',
        filename: '../external.html',
        chunks: ['external'],
        inject: "body"
    }))
    /*
     * ENTRY CONFIG
     *
     * Add 1 entry for each "page" of your app
     * (including one that's included on every page - e.g. "app")
     *
     * Each entry will result in one JavaScript file (e.g. app.js)
     * and one CSS file (e.g. app.css) if your JavaScript imports CSS.
     */
    .addEntry('layout', './assets/layout/index.js')
    .addEntry('external', './assets/layout/external/index.js')
    //.addEntry('page1', './assets/page1.js')
    //.addEntry('page2', './assets/page2.js')

    // When enabled, Webpack "splits" your files into smaller pieces for greater optimization.
    .splitEntryChunks()

    // will require an extra script tag for runtime.js
    // but, you probably want this, unless you're building a single-page app
    .enableSingleRuntimeChunk()

    .addAliases({
        "@core": path.resolve(__dirname, 'assets/core/'),
        "@layout": path.resolve(__dirname, 'assets/layout/'),
        "@components": path.resolve(__dirname, 'assets/components/'),
    })

    /*
     * FEATURE CONFIG
     *
     * Enable & configure other features below. For a full
     * list of features, see:
     * https://symfony.com/doc/current/frontend.html#adding-more-features
     */
    .cleanupOutputBeforeBuild()
    .enableBuildNotifications()
    .enableSourceMaps(!Encore.isProduction())
    // enables hashed filenames (e.g. app.abc123.css)
    .enableVersioning(Encore.isProduction())

    // enables @babel/preset-env polyfills
    .configureBabelPresetEnv((config) => {
        config.useBuiltIns = 'usage';
        config.corejs = 3;
    })

    // enables PostCSS support
    .enablePostCssLoader()

    // enables Sass/SCSS support
    //.enableSassLoader()

    // uncomment if you use TypeScript
    //.enableTypeScriptLoader()

    // uncomment to get integrity="..." attributes on your script & link tags
    // requires WebpackEncoreBundle 1.4 or higher
    .enableIntegrityHashes(Encore.isProduction())

    // uncomment if you're having problems with a jQuery plugin
    //.autoProvidejQuery()

    // uncomment if you use API Platform Admin (composer require api-admin)
    //.enableReactPreset()
    //.addEntry('admin', './assets/admin.js')
;

module.exports = Encore.getWebpackConfig();