Headers API doesn't ignore case

[cyco130]

Describe the bug
Headers API should ignore letter cases but it doesn't. It causes many failures in Rakkas's integration tests.

To Reproduce
Run the following snippet:

const headers = new Headers();
headers.append("X-Test", "1234");
console.log("HEADERS", Object.fromEntries(headers.entries()));
console.log(headers.get("X-Test")); // Prints 1234
console.log(headers.get("x-test")); // Prints undefined

Expected behavior
I expect headers.get("x-test") to be equal to headers.get("X-Test").

Information:

• OS: Linux Mint
• Browser: Doesn't apply
• Version: 0.3.3

[QuiiBz]

Good catch! As a note, the implementation is defined here:

• lagon/packages/js-runtime/src/runtime/fetch.ts

  Line 4 in eebaf9d

  export class Headers {

  
  Not sure what's the best solution to fix this bug:
• Update get/append operations to find by transforming all headers to lowercase
• Always store the headers in upper/lowercase. That means the user might be surprised because we modify a header key on his behalf (it shouldn't change anything at the end, because any get operation will return the right header value no matter the case of the header key)

[cyco130]

Sounds like a perfect first PR opportunity :)

I haven't looked at the spec but Chrome, Firefox, Deno, and Node (with --experimental-fetch) all return "x-test" for [...new Headers({ "X-Test" : "1234" })][0][0]. The end user has very few ways to observe the behavior so I think storing everything in lowercase should be OK.

Would you accept a getSetCookie or getAll("set-cookie") implementation in the same PR or should we open a discussion issue for that?

[cyco130]

The spec also seems to approve of storing in lowercase.

[QuiiBz]

The spec also seems to approve of storing in lowercase.

Sounds great. Let's go this way, and let me know if you want to submit a PR for this :)

Would you accept a whatwg/fetch#1346 implementation in the same PR or should we open a discussion issue for that?

I would prefer opening a new issue, since it's not directly related to this bug.