Bug 231194 – HTMLSelectElement's change event does not have composed true set

• Status: RESOLVED
• Resolution: WONTFIX
• Component: New Bugs

[Elliott Marquez]

The `change` event on HTMLSelectElement has {bubbles: true, composed: false} unlike the `input` event which has `{bubbles: true, composed: true}` This means that if someone wants to listen for the change event from a <select> inside of the shadow root of a custom element, then it will not propagate through the composed shadow tree.

Live repro:
https://jsbin.com/zahocodiwo/edit?html,output

Steps to repro:

1. Place a <select> element with <option>s inside a shadow root
2. Add an event listener for the `change` event on the shadow root host
3. toggle between options in the <select>
4. observe that the `change` event listener is not called.

Expected behavior:

the event listener is called and the change event has `composed: true`

Actual behavior:

The event listener is not called and the change event has `composed: false`

[Aditya Keerthi]

The WHATWG concluded that the `change` event should not be composed. [1]

Our behavior matches Chrome and Firefox.

[1] https://github.com/whatwg/html/issues/5453#issuecomment-885222243