Get the `detail` field from a custom event about bs-webapi-incubator HOT 4 CLOSED

detail is a property only available on CustomEvent, not on Event. And to implement it safely we'd have to add a type parameter to Dom.customEvent. Not sure if that's worth it, or if it's better to have consumers extend Dom.customEvent and implement their own properly typed detail accessor.

What's your use case?

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I'm trying to use this too, currently for web components.

I doubt it's possible to ensure safety as addEventListener can't change its type signature depending on whether it's listening for a custom event.

The best option I can think of is to accept an eventName type instead of a string for addEventListener:
type eventName = | Base(string) | Custom(string, 'a);
Or something to distinguish binding to regular events and custom events.

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How would you specify what 'a is?

We could just add an addCustomEventListener as well:

[@bs.send.pipe: t] external addCustomEventListener : string => (customEvent('a) => unit) => unit = "addEventListener";

But the problem remains, you still don't have a way of ensuring that 'a is a concrete type.

Apart from that, we have to consider how to construct custom events and how to transition from not having a type variable to having one, since the type actually lives in bs-platform, while the bindings live here.

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Closing as I don't see a type-safe way to get the detail type from an addEventListener handler given our current bindings. This will probably require more specialized bindings for addEventListener, that constrain the type more for custom events.

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