Chrome autocomplete incorrectly triggers actions with keydown events (regardless of KeyboardEvent filters)

[MatheusRich]

When using a Stimulus action like:

<button data-action="keydown.meta+k@window->search#open">

In Google Chrome, clicking an input’s autocomplete suggestion unexpectedly triggers the controller action even though no key is pressed.

It seems that Chrome dispatches an Event with type === "keydown", but it is not an instance of KeyboardEvent. This happens regardless of the key filter (and using @window or not).

Reproduction

Use this CodePen: https://codepen.io/matheusrich/pen/xbwOOqm

Steps:

1. Click inside the input field and wait for the autocomplete list to appear.
2. Pick a suggestion from the autocomplete list.
3. ✅ Stimulus incorrectly triggers the action

Workaround

On my controller, I'm using this to prevent this behavior for now

if (event.type == "keydown" && !(event instanceof KeyboardEvent)) return

I'll submit a fix to for this on Stimulus.

Chrome Version 138.0.7204.169 (Official Build) (x86_64)

[tsmd]

This issue is probably a duplicate of #743.