Page refresh after endpoint POST triggers "Are you sure?" dialog on Safari

[angrytongan]

Describe the bug

Refreshing a page after doing a POST to a page endpoint on safari triggers the "Are you sure you want to send a form again?" dialog. It looks like Safari wants to do the original POST again, and not the subsequent GET. On Chrome, the GET is actioned, and there is no repeat POST.

Reproduction

https://github.com/angrytongan/safari-endpoint-post-bug

Logs

No response

System Info

System:
    OS: macOS 11.6.5
    CPU: (4) x64 Intel(R) Core(TM) i5-4260U CPU @ 1.40GHz
    Memory: 320.74 MB / 4.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 17.9.0 - /usr/local/bin/node
    Yarn: 1.22.18 - /usr/local/bin/yarn
    npm: 8.5.5 - /usr/local/bin/npm
  Browsers:
    Chrome: 100.0.4896.127
    Safari: 15.4
  npmPackages:
    @sveltejs/adapter-auto: next => 1.0.0-next.39
    @sveltejs/kit: next => 1.0.0-next.322
    svelte: ^3.44.0 => 3.47.0

Severity

annoyance

Additional Information

No response

[johnwalshuk]

Hey, the Post-Redirect-Get pattern will resolve this, see: https://en.wikipedia.org/wiki/Post/Redirect/Get

[Rich-Harris]

Interesting — I wish I was surprised at such different behaviour for something so fundamental, but I'm not. PRG does result in consistent behaviour, but it means that the body returned from the post handler is disregarded — instead the get handler must reflect the mutation from the post.

I'm not sure if there's anything that SvelteKit can do to normalise the behaviour. At the very least, we should document the inconsistency.