improve published package with rollup

[travi]

• https://github.com/rollup/rollup
• https://medium.com/@tarkus/how-to-build-and-publish-es6-modules-today-with-babel-and-rollup-4426d9c7ca71#.gg4jri97r

[travi]

https://github.com/rtsao/babel-preset-es2015-node

[travi]

the browser field seems to be pretty straightforward, but is also spec-ed out here

[travi]

defining jsnext:main is a bit less clear. the best summary appears to be:

jsnext:main will point to a module that has ES2015 module syntax but otherwise only syntax features that node supports.

My open questions:

• only syntax that which version of node supports (is the approach mature enough to consider engines from the package.json?)
• What steps need to be taken for the consuming node app to use this version (is babel aware?)

References:

• https://github.com/rollup/rollup#can-i-distribute-my-package-as-an-es6-module
• https://github.com/rollup/rollup/wiki/jsnext:main
• jsnext:main should point to a distributable ES6 bundle reduxjs/redux#1042 (comment)
• Will/does Webpack support "module" field? webpack/webpack#1979

[travi]

i really like the idea of a jsnext:browser, but that doesn't seem to be a thing quite yet.

rollup/rollup-plugin-node-resolve#8

[travi]

https://nolanlawson.com/2015/10/19/the-struggles-of-publishing-a-javascript-library/