Set default options for dispatchCustomEvent

[fbring]

Explain the problem

The usage of dispatchCustomEvent accepts 3 arguments:

1. eventName
2. details
3. options

I think that in almost every case dispatchCustomEvent will be used for communicating with a parent component and therefore we need to set the bubbles: true option manually.

I searched in our current codebase for usage of dispatchCustomEvent:

• 6/6 use bubbles: true
• 4/6 use cancelable: true

Expected Behaviour

I would like to see at least the bubbles: true as a default option. Maybe it makes sense to set cancelable: true as well.

Actual Behaviour

Set all options manually inside the options object.

[byara]

In most cases, we want this behavior, but isn't that a breaking change?

[pago]

I'm wondering whether we really should be overwriting the DOM here. Making bubbles explicit has some benefits for readability (you clearly communicate the intend). I'd have a hard time to identify any valid use case for a non-bubbling event. So you could also say its a bugfix.
Theoretically bubbles: false might be useful for reusable ref-handlers but the ergonomics of those are currently not good enough so I doubt anybody uses that.

=> To me it's a bugfix. bubbles: false is very unlikely to have the expected behaviour and is most likely a cause of bugs. @byara do you agree?

What I do know for sure is that we shouldn't make cancelable a default. I doubt that we have a single line of code dealing with an event that has been cancelled. And if you don't deal with that case then there's no sense in marking an event as cancelable.

[byara]

@pago agreed. I cannot come up with a case that I would set the bubbles: false.