[Webkit-unassigned] [Bug 235911] New: Select on iPad doesn't refresh dropdown UI after an option is removed

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=235911

            Bug ID: 235911
           Summary: Select on iPad doesn't refresh dropdown UI after an
                    option is removed
           Product: WebKit
           Version: Safari 15
          Hardware: iPhone / iPad
                OS: iOS 15
            Status: NEW
          Severity: Critical
          Priority: P2
         Component: Layout and Rendering
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: m.goleb+bugzilla at gmail.com
                CC: bfulgham at webkit.org, simon.fraser at apple.com,
                    zalan at apple.com

This is an issue reported as happening in the wild on a project using AngularJS. AngularJS is EOL now and will not see a new release. Unless iPad Safari is fixed, this will forever stay broken in the official AngularJS.

On an iPad with the latest iPadOS 15.3, if you have a `<select>` element on the page and you perform the following steps:
1. Open the select dropdown by clicking on it (then optionally close it, it doesn't matter)
2. Programmatically remove an option by invoking `select.remove(0)`
3. Open the select dropdown again
you'll see that the dropdown still shows all the original options despite the select DOM being properly updated.

When that issue happens, it's sometimes very hard to force Safari to update the UI state properly. Opening the same select dropdown repeatedly doesn't update it. Some CSS actions like setting the select height help but only if the dropdown is opened after this height update so programmatic workarounds like "set select height to 10px, force style recalc, reset select height" don't work. If you have multiple select elements on the page and you open another one, the UI state cache is apparently cleared and opening the first select now shows the correct options. Again, this is not something that can be done programmatically by a library.

Weirdly, this only happens on iPad. It works fine on macOS & on an iPhone. On an iPad, it happens both on a real device (tested on iPad 9th generation) on iPadOS 15.3 and on an iPad Pro (11-inch) simulator with iPadOS 15.2. I was also able to reproduce on an iPadOS 14.5 simulator but not on the iPadOS 13.5 one.


A live test case: Test case showing the issue: https://output.jsbin.com/fihujuq/8.

The AngularJS issue: https://github.com/angular/angular.js/issues/17168

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