Gruntfile.js

module.exports = function(grunt) {

    require('matchdep').filterDev('grunt-*').forEach(grunt.loadNpmTasks);

    // Project configuration.
    grunt.initConfig({
        pkg: grunt.file.readJSON('package.json'),
        webpack: {
            dist: {
                entry: './es6/app.es6',
                output: {
                    path: 'es6',
                    filename: 'bundle.es6'
                },
                module: {
                    loaders: [
                        { test: /\.es6|\.js$/, exclude: /node_modules/, loader: 'babel-loader' }
                    ]
                }
            }
        },

        babel: {
            // options: {
            //     sourceMap: false
            // },
            dist: {
                files: {
                    'es5/script.js': 'es6/bundle.es6'
                }
                // Howto: transpile and copy multiple files to a new dest
                // expand: true,
                // cwd: 'es6/',
                // src: ['**/*'],
                // dest: 'es5/',
                // ext: '.js'
            }
        }
    });

    // Default task(s).
    grunt.registerTask('default', ['webpack', 'babel']);

};