title: What is the easiest way to pack and publish an npm module?
body: <p>I've been researching about this topic, many things I read are overlapping with babel, webpack, rollup, and even browserify. 
  What's the standard way (or most common way) to easily publish source code written in es6 that can be consumed in browser with the script tag and in node with require? 
  Equally confusing is how many versions are actually needed? I read that there are three - umd, cjs and original source, but isn't umd covering cjs already? And then I also see there's an es version(folder), which I think is identical to the source, why is that needed?</p>