Mike Bostock

D3 examples as reusable functions! Ready for import or copy-paste.

D3 Charts

Force-directed graph layout using velocity Verlet integration.

d3-force

Explore and explain patterns in quantitative data using D3 and Vega.

Observable

Visualization

In what world is this valid javascript?

You're trying to return a value from a code block which has been assigned to a variable. It almost looks like you're trying to create an arrow function.

Where did you learn to code like this? It's fantastic. I tested some similar code in JSFiddle. Apparently it's totally invalid as javascript. See for yourself. https://jsfiddle.net/4ekrLo5t/

But I see that here, on observablehq, it works.

There is some sort of terrible magic in the air.

ɐʞoʎǝH

Yes! See https://observablehq.com/@observablehq/observables-not-javascript for an overview of that magic.