Add runtime conditions into package.json

[yusukebe]

Hono supports JavaScript multi-runtime, and WinterCG defines the standard keys for that (c.runtime already returns the runtime key on which the app runtime running). Then I know we can include the keys in package.json for specifiying conditions like Wrangler doing:

• https://twitter.com/jasnell/status/1619450523912126464
• Prioritise workerd condition when bundling cloudflare/workers-sdk#2629

I don't know yet what effect it will have on Hono, but I think it is good we will challenge it.

[yusukebe]

Hi @yujong-lee !

If you are interested, check it out.

[yusukebe]

The new version of Wrangler supports the conditional exports field.

• https://github.com/cloudflare/wrangler2/releases/tag/wrangler%402.9.0

And Bun also looks up the exports field if it has bun or not:

• https://bun.sh/blog/bun-v0.5.0#module-resolution-changes

[yusukebe]

According the project:

https://github.com/cloudflare/workers-sdk/blob/main/fixtures/isomorphic-random-example/package.json

we can write the package.json like this:

{
  "name": "isomorphic-random-example",
  "version": "0.0.1",
  "private": true,
  "exports": {
    "node": "./src/node.js",
    "workerd": "./src/workerd.mjs"
  }
}

This is a very interesting way to have references to, for example, workerd.js for workerd, deno.js for deno, and bun.js for bun. But, in the case of Hono, all runtimes only need to refer to one index.js, so it doesn't make much sense:)

[yusukebe]

It does not seem necessary to go this far.