Initial version

[rreusser]

This component includes the changes discussed. The high points:

• plotly.js is a peer dependency
• the main export (import Plot from 'react-plotly.js') is a react component that will bundle plotly.js. It is documented here.
• import factory from 'react-plotly.js/factory' is a function with which you can BYO plotly.js. The peer dependency will give you a warning but you may ignore it, as noted in the readme.
• Finally, I've added a note on the roadmap so that people know what to expect in the near future.

(A small note that import { factory } from 'react-plotly.js' would not work. ES6 means static resolution of modules, and static resolution means there can be no option whether to import or not import plotly.js.)

TODO:

• move nontrivial package.json scripts to js script tasks
• check windows compatibility of build scripts
• does anyone use bundled react components via script tags? I followed the recommendation because it's a thing you can do, but perhaps it should get the 🔪
• publish

/cc @bpostlethwaite @nicolaskruchten @chriddyp @etpinard @monfera @alexcjohnson

[rreusser]

Going ahead an merging this. Leaving publish details as a separate issue.