webpack.config.js

const Encore = require('@symfony/webpack-encore');

// 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
    .setOutputPath('public/')
    .setPublicPath('/')
    .addEntry('app', './assets/app.js')
    .splitEntryChunks()
    .enableSingleRuntimeChunk()
    .cleanupOutputBeforeBuild()
    .enableSourceMaps(!Encore.isProduction())
    .enableVersioning(Encore.isProduction())
    .configureBabelPresetEnv((config) => {
        config.useBuiltIns = 'usage';
        config.corejs = 3;
    })
    // copying govuk-frontend images
    .copyFiles(
        {
            from: './node_modules/govuk-frontend/govuk/assets/images',
            to: 'images/[path][name].[ext]',
        })
    // copying govuk-frontend fonts
    .copyFiles(
    {
        from: './node_modules/govuk-frontend/govuk/assets/fonts',
        to: 'fonts/[path][name].[ext]',
    })
    .enableSassLoader(function(options) {
        options.sassOptions = {
            includePaths: [
                'node_modules/govuk-frontend/',
            ],
            outputStyle: 'compressed',
        }
    })

    // 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();