Safari has strange behavior, how to fix them?

I'm a developer. My code is working as expected on Google Chrome and Firefox. But I tried it on Safari and it's a disaster. I would like to know what's wrong, what is different in those cases, and if I should report bugs. My coding objective is to select options in the list. This will automatically select options for the two others in the list. One can be edited, not the second one. This is fine on Chrome and Firefox, as I said. On mobile (iOS 18.5, iPhone 16e): - The list that can be edited is well auto-selected, not the second one - The second one can be edited (even if it should not) I enabled dev mode, but it doesn't seem to change anything. On my Mac Mini (macOS 15.5): - The list that can be edited is well auto-selected, not the second one - Cannot edit the second list, so it's fine - I change the code of a JS file, refresh page -> no change. I go to Chrome, refresh -> see changes. Is there a specific refresh needed?