Use lowercase headers

[HiiiiD]

Changes

What does this PR change? Link to any related issue(s).

Undici returns headers in lowercase as it can be seen here. This PR updates the content-type check in order to use the lowercase version.

How to Review

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Checklist

• Unit tests updated
• README updated
• examples/ directory updated (if applicable)

[drwpow]

Does this fix a problem? I’m not sure why this is needed

[timothymctim]

This would fix an issue for me: my backend server sends the Content-Type header in lower case. Since key indices in JavaScript are case sensitive, this would fix it for me, but this fix would break the code for others as it wouldn’t match Content-Type any more. The following code would normalize the header key first before selecting and using it.

let contentType = res.headers[Object.keys(res.headers).find(key => key.toLowerCase() === 'content-type')]
contentType = Array.isArray(contentType)
    ? contentType[0]
    : contentType;

[HiiiiD]

As I said in the first PR comment, Undici returns all headers in lowercase, so that's not an issue @timothymctim

[timothymctim]

As I said in the first PR comment, Undici returns all headers in lowercase, so that's not an issue @timothymctim

Indeed, that’s the case! Sorry, my bad :)

[drwpow]

@all-contributors please add @HiiiiD for code, test

[allcontributors]

@drwpow

I've put up a pull request to add @HiiiiD! 🎉