feat: introduce Accepts Helper

[sor4chi]

Author should do the followings, if applicable

Resolve #1792
Resolve #1897

• Add tests
• Run tests
• yarn denoify to generate files for Deno

[sor4chi]

Hi, @yusukebe. I tried to implement the accept helper!

[yusukebe]

Hi @sor4chi

Almost looks good. But, I want you to write some code using real apps like this:

const app = new Hono()

app.get('/', (c) => {
  const result = matchAccept(c, {})
  return c.json({
    result,
  })
})

const res = await app.request('/', {
  headers: {
    //...
  },
})

expect(res.json()).toEqual({})

[sor4chi]

These are proxy usecases

app.get("*", async (c) => {
  const encoding = matchAccept(c, {
    header: "Accept-Encoding",
    supports: ["gzip", "deflate"],
    default: "identity",
  });
  const res = await fetch(`${ORIGIN_URL}/${c.req.path}`, c.req.raw);

  if (encoding === "gzip") {
    return res.body?.pipeThrough(new CompressionStream("gzip"));
  }

  if (encoding === "deflate") {
    return res.body?.pipeThrough(new CompressionStream("deflate"));
  }

  return res;
});

app.get("*", (c) => {
  const supportedLangs = ["en", "ja", "zh"];
  const lang = matchAccept(c, {
    header: "Accept-Language",
    supports: supportedLangs,
    default: "en",
  });

  const isLangedPath = supportedLangs.some((l) => c.req.path.startsWith(`/${l}`));
  if (isLangedPath) {
    return fetch(c.req.raw);
  }

  return c.redirect(`${ORIGIN_URL}/${lang}${c.req.path}`)
})

[yusukebe]

@sor4chi

Thanks. Could you add tests that are using app like the code?

[sor4chi]

@yusukebe Alright, added!

[yusukebe]

@sor4chi

Great work! Last thing. Please remove the warnings by linter.

[yusukebe]

@sor4chi

Is this ready?

[sor4chi]

@yusukebe yes, please.

[yusukebe]

I'm not sure if matchAccept is the best name. I think accepts simply is better.

[yusukebe]

@sor4chi

I've commented about naming. Check it!

[sor4chi]

@yusukebe Thank you for reviewing, fixed it!

[yusukebe]

Okay! Let's land it. Thanks for contributing.

[yusukebe]

Hi @sor4chi !

Could you write the website document for this Accepts Helper?