Our interactives at La Silla Vacia are developed independently from the CMS and bundled into self-assembling Javascript files using webpack. They are both discrete--requiring no dependencies--and discreet--interfering as little as possible with the rest of the page.
The use of webpack loader, including babel, allows developers to include all the (reasonably-sized) files they need in debug.js: HTML, CSS, PostCSS, and any modern Javascript conventions.
The templating is done with Preact.js. A lightweight React alternative.
Please see the wiki for instructions on installation and usage.