Using 'active script' for determining import: URL scope is brittle

[bicknellr]

(relevant text: https://github.com/domenic/import-maps/blob/e4dd5e3b070ca5bd56bf65bfa01085045207a52c/spec.md#modifications-to-the-url-parser-for-import-urls)

Using 'active script' to determine the scope for a particular import: URL seems to break down easily when passing URLs from scripts in one scope to scripts in another:

./lib.js, in scope A:

export makeImage = url => {
  const image = document.createElement('img');
  image.src = url;
  return src;
}

./caller.js, in scope B:

import {makeImage} from "lib/lib.js";
document.body.appendChild(makeImage("import:somewhere/image.png"));

If caller.js and lib.js are in separate scopes, but the deciding factor for which scope applies to a particular import: URL is based on the 'active script' at the time the import: URL string would be consumed for resolution, then import:somewhere/image.png would be resolved in scope A, used by lib.js, rather than scope B. How can a caller one scope provide an import: URL to another scope that resolves to the network URL expected by the caller?

I think this would require some kind of URL resolution function ("import.resolve") but doing so seems to be currently precluded by other problems (CORS, async).

[domenic]

This seems like a dupe of #75, do you agree?

[bicknellr]

Yup, this is a dupe.