Gruntfile.js

/* eslint-env node */
const babel = require("rollup-plugin-babel");
const nodeResolve = require("rollup-plugin-node-resolve");
const commonjs = require("rollup-plugin-commonjs");

module.exports = (grunt) => {
    "use strict";

    grunt.initConfig({
        jasmine: {
            components: {
                src: [
                    "components/*js"
                ],
                options: {
                    specs: "tests/specs/*Spec.js"
                }
            }
        },
        rollup: {
            options: {
                plugins: () => {
                    return [
                        nodeResolve({ jsnext: true, main: true }),
                        commonjs(),
                        babel({
                            exclude: "node_modules/**",
                            presets: ["es2015-rollup"]
                        })
                    ];
                }
            },
            main: {
                dest: "build/main.js",
                src: "src/main.js" // Only one source file is permitted
            }
        },
        concat: {
            options: {
                separator: ";\n"
            },
            dist: {
                src: ["node_modules/webcomponents.js/CustomElements.min.js", "build/main.js"],
                dest: "dist/x-div.js"
            }
        },
        watch: {
            demo: {
                files: "demo/**/*.*",
                tasks: ["dist"],
                options: {
                    livereload: true
                }
            },
            src: {
                files: "src/**/*.*",
                tasks: ["dist"],
                options: {
                    livereload: true
                }
            }
        },
        open: {
            demo: {
                path: "demo/index.html",
                app: "google-chrome"
            }
        }
    });

    grunt.registerTask("travis", ["jasmine"]);

    grunt.loadNpmTasks("grunt-rollup");
    grunt.loadNpmTasks("grunt-contrib-concat");
    grunt.loadNpmTasks("grunt-contrib-watch");
    grunt.loadNpmTasks("grunt-open");

    grunt.registerTask("default", ["jshint"]);
    grunt.registerTask("dev", ["dist", "open", "watch"]);

    grunt.registerTask("dist", ["rollup", "concat"]);
};