Just in case people were wondering, the site seems to have been overwhelmed for the past 10-15 minutes. But there's a YouTube demo of the tech https://news.ycombinator.com/item?id=16275040

I guess an oversimplified description would be that this is like a Jupyter Notebook specifically for JavaScript. Libraries like D3 are pre-loaded and immediately accessible. Am definitely interested in hearing the details about what it is built with and medium to long-term plans for the service.

Note that the Jupyter Notebook service generally requires you to be installing and running Python etc. on your own computer. Jumping into an Observable notebook is as easy as opening your browser and signing in via GIthub

I wrote more about the motivation for Observable (formerly d3.express) last year: https://medium.com/@mbostock/a-better-way-to-code-2b1d2876a3...

It’s easy to use D3 within Observable, but it’s not pre-loaded or specifically built-in. Any browser library published to npm can be loaded via require (for AMD) or dynamic import (for ES modules). I’ve published a bunch of notebooks with D3 but you’ll find other ones with THREE.js, Vega-Lite, Leaflet and other libraries.