How to import a path with npm specifiers?

[outloudvi]

It's apparently possible to achieve this:

import uniq from "https://cdn.skypack.dev/[email protected]/uniq"
console.log(uniq([1,2,2,3])) // [1,2,3]

With the npm specifiers, it's also possible to import a whole package from npm:

import uniq from "npm:[email protected]"
console.log(uniq([1,2,2,3])) // [1,2,3]

Do we have a way to achieve:

// It currently doesn't work for me
import uniq from "npm:[email protected]/uniq"
console.log(uniq([1,2,2,3])) // [1,2,3]

[bartlomieju]

You should be able to use import map like so:

{
    "imports": {
       "lodash/": "npm:/[email protected]"
    }
}

import uniq from "lodash/uniq";

This was fixed in #16754, notice the slash after npm: - it's required in import maps to map to a folder.

[Conaclos]

Is it the recommended way to import a npm module as a library author? If I understand correctly, importing a dependency in deno does not take the dependency's import map into account?

[bartlomieju]

Thanks! Seems that it works, but only with a .js suffix on the import:

import uniq from "lodash/uniq.js"
console.log(uniq([1,2,2,3])) // [1,2,3]

It also asked me to add a trailing slash at import_map.json:

{
    "imports": {
       "lodash/": "npm:/[email protected]/"
    }
}

Then it can give me:

$ deno run --importmap=import_map.json ./test.ts
[ 1, 2, 3 ]

Ah yes, if these are ES modules then the .js extension is indeed required.

[bartlomieju]

Is it the recommended way to import a npm module as a library author? If I understand correctly, importing a dependency in deno does not take the dependency's import map into account?

That's correct, library authors are not meant to use import maps - they do not "cascade" or "stack", only the final import map is applied.

[Conaclos]

That's correct, library authors are not meant to use import maps - they do not "cascade" or "stack", only the final import map is applied.

Is there any plan to make it cascading?

[bartlomieju]

Not unless the WICG reaches a consensus on this feature. See issues on https://github.com/WICG/import-maps

[spencerhakim]

I think your example should work as-is, #15578 should have added support for this back in August. If it isn't working, you might want to file a bug report.

[outloudvi]

Thanks for your pointing to that PR! I see that precisely described my need, but probably something changed over the later commits.