# webapp/resources/assets/js/testtest.js
export default function bar() {
    console.log("hello");
}



# webapp/resources/assets/js/index.js
import bar from './testtest';

bar();



# webapp\webpack.mix.js
let mix = require('laravel-mix');

/*
 |--------------------------------------------------------------------------
 | Mix Asset Management
 |--------------------------------------------------------------------------
 |
 | Mix provides a clean, fluent API for defining some Webpack build steps
 | for your Laravel application. By default, we are compiling the Sass
 | file for your application, as well as bundling up your JS files.
 |
 */

mix.js('resources/assets/js/index.js', 'dist/')



# webapp/index.html
<script type="module">
        import bar from './dist/index.js';

        bar();
</script>