"XMLHttpRequest is not defined" on sveltekit endpoints when deployed on Vercel

Bug report

Describe the bug

Using the client for auth or for querying the database in a sveltekit endpoint throw an error :

{
  data: null,
  error: ReferenceError: XMLHttpRequest is not defined
      at file:///var/task/server/app.mjs:2522:21
      at new Promise (<anonymous>)
      at fetch2 (file:///var/task/server/app.mjs:2517:16)
      at file:///var/task/server/app.mjs:2646:7
      at new Promise (<anonymous>)
      at file:///var/task/server/app.mjs:2645:12
      at Generator.next (<anonymous>)
      at file:///var/task/server/app.mjs:2619:67
      at new Promise (<anonymous>)
      at __awaiter$8 (file:///var/task/server/app.mjs:2601:10)
}

To Reproduce

I made a repository exposing the issue : https://github.com/Pixselve/supabase-sveltekit-endpoints Click on a button to fetch the endpoint and observe the cloud functions logs on Vercel.

Expected behavior

Requests should not fail and should give the appropriate data.

System information

• OS: Vercel Node.js Runtime
• Version of supabase-js: 1.10.0
• Version of Node.js: 14

[sbutler-gh]

@sbutler-gh I think your repo isn’t actually using the up-to-date version of @supabase/supabase-js, see here:

sbutler-gh/just-start@c32ecef/package-lock.json#L325-L326

It appears it’s using version 1.24.0, and the ability to pass in a custom fetch implementation was added in 1.27.0 (and 1.28.1 is the latest version).

After running npm update to update packages and re-deploying, it now works as expected in production on Cloudflare Pages! (using fetch: (...args) => fetch(...args), didn’t try the other syntaxes yet.). Thank you SO MUCH @jacobwgillespie ! I can’t thank you enough!

[kiwicopple]

Thanks to a very impressive series of PRs from @jacobwgillespie , this now has a workaround

https://github.com/supabase/supabase-js/releases/tag/v1.27.0

after upgrading to v1.27.0 you can use a custom fetch implementation

import { createClient } from '@supabase/supabase-js'

// Provide a custom `fetch` implementation as an option
const supabase = createClient('https://xyzcompany.supabase.co', 'public-anon-key', { fetch: fetch })

Jacob - if you send your details (and tshirt size) to [e-mail] we will send you a nice package 🙏