Data serialization is broken if you are using full URL to API on your hostname

[stalkerg]

Describe the bug

My API is on the same hostname but in sub path "/api". My fetch do things like fetch('https://my.site/api/get_user') .
The URL from this fetch is testing on the server side is here https://github.com/sveltejs/kit/blob/master/packages/kit/src/runtime/server/page/load_data.js#L190 and removing the hostname from the URL because the origin is the same, but the client trying to search the full path by selector because we use fetch URL as is here https://github.com/sveltejs/kit/blob/master/packages/kit/src/runtime/client/client.js#L603 .

It raises the second request to API, from CSR.

Reproduction

In the load function, you should make a fetch with the full path to the same hostname.

Logs

No response

System Info

System:
    OS: Linux 5.4 Ubuntu 20.04.5 LTS (Focal Fossa)
    CPU: (12) x64 AMD Ryzen 5 3600 6-Core Processor
    Memory: 37.92 GB / 62.81 GB
    Container: Yes
    Shell: 5.0.17 - /bin/bash
  Binaries:
    Node: 18.12.1 - /usr/bin/node
    npm: 8.19.2 - /usr/bin/npm
  npmPackages:
    @sveltejs/adapter-node: 1.1.4 => 1.1.4 
    @sveltejs/kit: 1.3.9 => 1.3.9 
    @sveltejs/svelte-virtual-list: github:sveltejs/svelte-virtual-list => 3.0.1 
    svelte: 3.55.1 => 3.55.1 
    vite: ^4.0.4 => 4.0.4

Severity

serious, but I can work around it

Additional Information

No response

[stalkerg]

SvelteKit is thinking of exclusive hostname usage, but it's definitely wrong.

[teemingc]

My API is on the same hostname but in sub path "/api". My fetch do things like fetch('https://my.site/api/get_user') .

Can you confirm if your issue is similar to #8851 where using the SvelteKit provided fetch is unable to find APIs outside the framework on the same host?

If it is similar, it should be fixed by #8869

[stalkerg]

@s3812497 seems like I have no similar issue because I am using handleFetch, anyway I have no crash, in my case, just serialization is broken. I suppose is a different issue but on the same theme.

[teemingc]

@s3812497 seems like I have no similar issue because I am using handleFetch, anyway I have no crash, in my case, just serialization is broken. I suppose is a different issue but on the same theme.

Do you mind uploading an example project that reproduces this issue and the actual / expected behaviour?
I'd like to investigate further.

[stalkerg]

I will try. Also, it seems like #8851 it's about server.js, but my issue is about fetch in load function of +page.js.
But again, you can look into my links and it will be clear - SSR uses only path for a tag with data, but on CSR a browser trying to find this tag by full URL with the hostname.

I am not sure how to fix it... basically, we can't remove the origin if it's not a part of SvelteKit routes.

PS I am found a workaround - just remove the origin (protocol+hostname) if it's the browser inside handleFetch.

[stalkerg]

@s3812497 @dummdidumm thanks!

[teemingc]

@stalkerg thanks for filing the issue :)