Change the default user agent of nodejs

[renhiyama]

What is the problem this feature will solve?

https://esm.sh supports auto targeting the build (ie. bundling code for specific runtime) by looking at the user agent.
The user agent they support (and probably some other websites) is like Node/{version}. Deno too uses a similar user agent - Deno/{version}.

Since I don't see any specific user agent used officially by nodejs (other than the library name it uses, ie. undici on v18+ and node-fetch for below than v16), I would like to see a unified user agent system, considering nobody created an issue on this, I believe this wouldn't break any existing system, instead it would help unifying the system against everyone's code.

What is the feature you are proposing to solve the problem?

Use Node/{version} as the user agent by default. Promotes URL imports usage from https://esm.sh and having same name across codes and having similar agent to Deno.

What alternatives have you considered?

I work on my own URL imports implementation, so I'm free to use URL imports from nodejs v16, have Node/* as my user agent and fix stuff/improve performance. Incase anyone is interested, check out @reejs/imports on npm.

[aduh95]

Since you mention <esm.sh>, I guess you are talking about --experimental-network-imports flag, right? FWIW it uses neither Undici nor node-fetch, it's a simple require('node:https').get call. ATM it doesn't use any user-agent header:

node/lib/internal/modules/esm/fetch_module.js

Lines 123 to 127 in 9658d84

	const handler = parsed.protocol === 'http:' ? HTTPGet : HTTPSGet;
	const result = (async () => {
	const req = handler(parsed, {
	headers: { Accept: '*/*' },
	});

I don't see a problem with adding one, if someone opens a PR adding one, it's likely to land (unless there's a security objection or something like that, of course).

[Linkgoron]

Searching a bit in github, I found some things that test for undici (didn't do an exhaustive search, just a basic github search):
https://github.com/bangumi/server/blob/cb0a61dc4addad6ed139b24178fdee0c2acdca3e/web/mw/ua/new.go#L63C1-L63C1
https://github.com/omrilotan/isbot/blob/ce32a82482479165b3d11f436c7df6d7fe2671ab/fixtures/crawlers.yml#L486

Not saying that this shouldn't be changed, just that there's probably code out there that already expects the current value(s).

[bnoordhuis]

See issue #43851 and pull request #43852.

I'll close this issue as a duplicate of the former and see the discussion in the latter - there's a distinct lack of consensus on whether to add the header 🤷