That might look something like adding the following to index.js:

(long names as this is probably a rare use case, and because these will end up on d3 itself)

export {
  fitExtent as geoProjectionFitExtent,
  fitSize as geoProjectionFitSize,
  fitWidth as geoProjectionFitWidth,
  fitHeight as geoProjectionFitHeight
} from "./projection/fit.js";

Then in the externally defined projection I could say:

import {
  geoProjectionFitExtent as fitExtent,
  geoProjectionFitSize as fitSize,
  geoProjectionFitWidth as fitWidth,
  geoProjectionFitHeight as fitHeight
} from 'd3-geo';

An alternative approach would be to finally offer a composite projections construct, that would deal with all the peculiarities (clipping, inverse, etc).

Interesting idea! Were there already discussions along the lines of a composite projections construct?

More sleuthing reveals another approach, though not sure if this is applicable https://github.com/d3/d3-geo-projection/blob/master/src/gilbert.js#L37

Maybe I could just say

  property("fitExtent");
  property("fitHeight");
  property("fitSize");
  property("fitWidth");

Considering submitting a PR with the change to expose these.

It looks like @HarryStevens has an alternative here https://observablehq.com/@washpostgraphics/geo-albers-usa-pr

It looks like @HarryStevens has an alternative here https://observablehq.com/@washpostgraphics/geo-albers-usa-pr

Yep, I just kept copy-pasting code from d3-geo until it stopped throwing errors.

apologies slightly off topic, but any chance of publishing https://observablehq.com/@washpostgraphics/geo-albers-usa-pr to npm for easier use off of observable?