Add package.json exports property

[gavinr]

This allows modern build systems (vite) to properly use the correct module type (ESM).

When this is not present, when using Chart.js in Sveltekit, when running a build it will give an error Named export 'Chart' not found. The requested module 'chart.js' is a CommonJS module, which may not support all module.exports as named exports.

More info: https://medium.com/swlh/npm-new-package-json-exports-field-1a7d1f489ccf
Also, for background: sveltejs/kit#1498 (comment) and sveltejs/kit#928 (comment)

[gavinr]

@benmccann does this resolve #9436 ?

[benmccann]

You'd also have to export package.json. Some build tools such as rollup-plugin-svelte will try to consume it. I'm not sure if this is exactly the right syntax, but I think you could do it with:

    ".": {
      "import": "./dist/chart.esm.js",
      "require": "./dist/chart.js",
    }
    "./package.json": "./package.json"

[kurkle]

I'm guessing helpers and auto need to be added too. And the type should not be changed, at least not before v4.

[benmccann]

do you have to add "type": "module"? I expect it might be a breaking change

[benmccann]

the tests are failing and I expect this line is why

[benmccann]

I haven't tested, but yes, I imagine it would fix that issue

[kurkle]

Discussion in #9405 is related (also has a workaround for vite).

[gavinr]

I worked around this issue by moving my Chart.register(...registerables); line into a place later in my code that gets created after the DOM: gavinr/stl-lambert-airport-data@b029b23

I'll close this PR for now since I don't have enough chartjs knowledge to push it forward, but I hope it can serve as inspiration for a future PR. Thanks!