fetch url now show the final url after all redirect

[ghost]

in nodejs v21.2.0
await globalThis.fetch('https://bit.ly/48b82fP').then(_ => _.url) just show the first redirect url:
https://l.facebook.com/l.php?u=https://f.theloadedbaze.com/%3Ffbclid%3DIwAR09e4iW8r6DAGuJbtEfepgIwLKm1zsIcavDGWT7gbFqyX4E56N7fL9pQNQ&h=AT1dnnHhh3K5JfViDpurjF0I833b7Fs5ukXQIDMNju_dSkagEbhuGB1zjjrFKuOZF2k6IU9MSTTwz0FlSoW761RP7xoRXBay0mUmD5bJYggSXdVlLwb4vOVlNXcM3oRnYMlwr_sh4RQ

But in node-fetch:
import fetch from 'node-fetch'
await globalThis.fetch('https://bit.ly/48b82fP').then(_ => _.url) show the final redirect url:
https://www.facebook.com/flx/warn/?u=https%3A%2F%2Ff.theloadedbaze.com%2F%3Ffbclid%3DIwAR09e4iW8r6DAGuJbtEfepgIwLKm1zsIcavDGWT7gbFqyX4E56N7fL9pQNQ&h=AT3Lwqzvo-lauSwVjMfI9Q5fw0WWGVojnuGIDzB_6p8f_8TP-A4MTOdU8LcjH_2OZ6o8auwyrtzF_XZOwH9EQ9ZBb5KlZz4D_x6DoR58t-FSfF3bNDoXfC8iqpPm-mAp-8aqMYwuFOQ

I want to know how to get the final url after all redirect in undici fetch link that in node-fetch?

[KhafraDev]

fetch will return the final redirect's url. If you can provide a minimal reproduction that doesn't use third party services I can look into it.

test code

import { once } from 'events'
import { createServer } from 'http'

const server = createServer((req, res) => {
  if (req.url === '/redirect') {
    res.writeHead(302, { Location: '/redirect2' })
    res.end()
    return
  }

  res.end('hello')
}).listen(0).unref()


await once(server, 'listening')

const r = await fetch(`http://localhost:${server.address().port}/redirect`)
console.log(r.url) // .../redirect2
server.close()

[ghost]

OK, the minimal test is I want to get the final URL after all the redirect https://bit.ly/48b82fP
the first redirect url is https://l.facebook.com/l.php?u=https://f.theloadedbaze.com/%3Ffbclid%3DIwAR09e4iW8r6DAGuJbtEfepgIwLKm1zsIcavDGWT7gbFqyX4E56N7fL9pQNQ&h=AT1dnnHhh3K5JfViDpurjF0I833b7Fs5ukXQIDMNju_dSkagEbhuGB1zjjrFKuOZF2k6IU9MSTTwz0FlSoW761RP7xoRXBay0mUmD5bJYggSXdVlLwb4vOVlNXcM3oRnYMlwr_sh4RQ

the first redirect url will redirect to final url
https://www.facebook.com/flx/warn/?u=https%3A%2F%2Ff.theloadedbaze.com%2F%3Ffbclid%3DIwAR09e4iW8r6DAGuJbtEfepgIwLKm1zsIcavDGWT7gbFqyX4E56N7fL9pQNQ&h=AT3Lwqzvo-lauSwVjMfI9Q5fw0WWGVojnuGIDzB_6p8f_8TP-A4MTOdU8LcjH_2OZ6o8auwyrtzF_XZOwH9EQ9ZBb5KlZz4D_x6DoR58t-FSfF3bNDoXfC8iqpPm-mAp-8aqMYwuFOQ

how to do that in nodejs builtin fetch aka undici.fetch to get the final url

[KhafraDev]

I'm sorry I can't help until there's a reproducible code example that doesn't use third party sites. Fetch by default will return the last redirect url.

[ghost]

what reproducible code example you want?
I test the case both node-fetch curl and python aiohttp can go to the last redirect url but undici just hang at the first redirect url. Please help.

[Uzlopak]

What does the spec say? What value should it have?

[mcollina]

what reproducible code example you want?

Write the server needed to reproduce the behavior in Undici.

[Uzlopak]

added a test case for this issue which proves, that the final url is set to the response.

#2716