Feature: support new package.json exports field

[jsamr]

exports field is a new standard which adoption will inevitably grow further as the ecosystem switches to full ESM as NodeJS 10 reaches EOL. It's probably best to support it before things break. Features:

• Export submodules with sub-path exports;
• Specific exports for both CJS and ESM modules.

Example of subpath exports from NodeJS docs:

{
  "type": "module",
  "name": "es-module-package",
  "main": "./main.js",
  "exports": {
    ".": "./main.js",
    "./submodule": "./src/submodule.js"
  }
}

The consumer of the library can now use:

import submodule from 'es-module-package/submodule';
// Loads ./node_modules/es-module-package/src/submodule.js

[kamleshchandnani]

Is there any plan to support this any time soon?

[alamothe]

Any workarounds?

[jamesgpearce]

Here's a workaround I used. In https://github.com/tinyplex/tinybase, I omit the "main" field in my package.json to prefer "exports".

To get this to work with Metro, I added a "react-native" field that points to the file. It's apparently not documented, but this is used as a higher-priority location than "main". "browser" is another option you might prefer.

Works a charm in tinyplex/tinybase#17:

[kamleshchandnani]

@robhogan any plans to support this? or we can enable it if it's behind some flag?