js-module-es2015-aka-es6

foo.js

function foo() {
  return 'Hi from foo!';
}

export default foo;

// or
// export default function foo() {
//   return 'Hi from foo!';
// }

js-module-es2015.js

//base
// http://unixpapa.com/js/key.html
// https://learn.javascript.ru/keyboard-events
// http://jsmodules.io/
// http://exploringjs.com/es6/ch_modules.html
//base-modules
// https://babeljs.io/docs/learn-es2015/#modules
// https://github.com/getify/You-Dont-Know-JS/blob/master/es6%20&%20beyond/ch3.md#the-new-way
// https://github.com/airbnb/javascript#modules
// https://medium.com/javascript-scene/common-misconceptions-about-inheritance-in-javascript-d5d9bab29b0a
//base-class
// https://babeljs.io/docs/learn-es2015/#classes
// https://github.com/getify/You-Dont-Know-JS/blob/master/es6%20&%20beyond/ch3.md#classes
// https://github.com/airbnb/javascript#constructors
//examples-modules
// https://github.com/babel/babel/blob/master/packages/babel-helper-call-delegate/src/index.js
// https://github.com/ccampbell/mousetrap/blob/master/mousetrap.js
//examples-class
// https://github.com/zenorocha/clipboard.js/blob/master/src/clipboard.js
// https://github.com/zenorocha/clipboard.js/blob/master/src/clipboard-action.js
// https://github.com/GoogleChrome/guitar-tuner/blob/master/src/scripts/libs/Toaster.js
// https://github.com/GoogleChrome/guitar-tuner/blob/master/src/scripts/guitartuner-core.js

main.js

//default
import foo from "foo";
//or named
// import { foo } from "foo";

foo();