Some feedback

[jasnell]

First off great to see explorations on this... some feedback.

Consider the following case...

{
  "path_prefix": "/node_modules",
  "packages": {
    "index.js": { "main": "src/index.js" },
  }
}

In an application that also has an index.js at it's root. What does import * from 'index.js' load? That is, how does this deal with naming collisions?

There's a danger here in recreating the hell that is Java classpaths.

Another approach to this could be to take a more generic http/http2 centric approach and allow an origin to declare client-side aliases for various resources. These would amount to a client side 302 or 303 response.

For instance:

HTTP/1.1 200 OK
Link: </node_modules/lodash.js>; rel="alias"; anchor="lodash"
Content-Type: application-js

import * from "lodash"

[justinfagnani]

Thanks!

I'm unsure why would you define a package named "index.js" and import as "index.js", why not just do:

import * from './src/index.js';

Which skips the package name map altogether.

Can you further describe why you wanted to define a file as a package?

[matthewp]

import * from 'index.js' should always load your index.js "package", because it's a bare module specifiers and bare specifiers are always looked up from the packagemap.

[ljharb]

It’d be for the same reasons people put symlinks in their node_modules or use a babel transform or webpack alias for the package root; but since the package map would only apply to bare imports - ie, only things that aren’t prefixed with a dot or protocol or slash, iirc - i don’t think there’d be any collision (as said here)

[matthewp]

@justinfagnani This is actually going to be /node_modules/index.js/src/index.js. I think @jasnell is bringing this up as a point because there would possibly be a collision if bare specifiers defaulted to normal URL rules.

Once #6 is complete hopefully that will clarify what happens in the case that a bare specifier doesn't match anything in the packagemap. My hope is that will error like it does today.

[justinfagnani]

Once #6 is complete hopefully that will clarify what happens in the case that a bare specifier doesn't match anything in the packagemap. My hope is that will error like it does today.

Oh definitely, that will throw.

[jasnell]

@matthewp ... yes, that's it exactly. The example was a bit off because I threw it together quickly but I'm glad the point came across.

[domenic]

The proposal has changed a lot, so let me close this. In the newest iteration, it's intentionally in-scope to allow remapping of URLs like ./src/index.js, as well as bare specifiers like index.js.