Implement fetch methods

[ronag]

Under lib/fetch/util.js we have a few helper methods that are pretty well documented in spec and and needs to be implemented:

• appendRequestOriginHeader
• appendFetchMetadata
• TAOCheck
• corsCheck
• crossOriginResourcePolicyCheck
• makePolicyContainer
• clonePolicyContainer
• determineRequestsReferrer

[ronag]

@szmarczak

[wong2]

I'd like to help!

[wong2]

Though I have a question: do we need to implement those browser related features such as cors, content security policy in undici fetch?

[ronag]

Some of those are indeed only browser related, you can either implement them if possible or add a note explaining why we don't need to implement them and return a appropriate value or an assertion.

[wong2]

I'd like to confirm what we think about cors related features, for example, mode is currently supported, while it's unimplemented in node-fetch. Do we want to support them as much as we can? Or are they unnecessary complexities?

[szmarczak]

Browser-related features might be useful when used with https://github.com/jsdom/jsdom but I don't have any use case for this.

[ronag]

I'd like to confirm what we think about cors related features, for example, mode is currently supported, while it's unimplemented in node-fetch. Do we want to support them as much as we can? Or are they unnecessary complexities?

We implement them because it's easy to just follow the spec literally.

[btakita]

It also supports isomorphic javascript.

[Viper-space]

Hey there is it okay if I try to implement some of them? :D