ES modules bring an official, standardized module system to JavaScript. It took a while to get here, though — nearly 10 years of standardization work. page 
We've been itching to embrace the ES6 module structures and maybe leave jQuery and CoffeeScript behind in the process. When node inventor Ryan Dahl announced that he was taking a similar fresh look at server-side javascript runtimes, of course we were interested.
Node.js creator Ryan Dahl voiced some deep misgivings about his server-side JavaScript runtime engine at the EU JS conference earlier this week in Germany. post
Michael Jackson Script (mjs) is a file name the node js community ascribed to ES6 modules.
One definitive answer (of many) for building javascript apps. Plausible recommendations and rationale, if you're just starting out (as of April 2018): use babel, webpack, & gulp. Wiki's current tools are equally plausible: coffeescript, browserify, & grunt. Related reading also recommend the yarn and webpack combination. blog
In the most ubiquitous programming ecosystem, modules have been shoehorned in where they were originally lacking. As of early 2018, nodejs gradually builds toward ECMAScript Modules. Guidance for transition from CommonJS to ESM: link
Jan Miksovsky is an designer/developer expert at component.kitchen on Web Components. Only interested in coding approaches that can be shared with other people. With emphasis on stylin and reuse. page
Proof of concept loading a web component into wiki. component.kitchen/elix github