How can I create a CustomEvent with detail object in Fable?

In Javascript it is possible to create a CustomEvent and include a second argument containing detail data to pass when the event is dispatched. For example:

let evt = new CustomEvent("hello", {
    detail: { name: "John" }
  });
elem.dispatchEvent(evt);

With Fable I can create a CustomEvent without the detail data as follows:

let evt = CustomEvent.Create "hello"
elem.dispatchEvent evt

The definition in Browser.Events is as follows:

type [<AllowNullLiteral>] CustomEventType =
    [<Emit("new $0($1...)")>] abstract Create : typeArg: string * ?eventInitDict: CustomEventInit -> CustomEvent
    [<Emit("new $0($1...)")>] abstract Create : typeArg: string * ?eventInitDict: CustomEventInit<'T> -> CustomEvent<'T>

But I can't work out how to create a CustomEventInit as I think this is an interface.

let details:CustomEventInit = { detail = {name = "John"}} //ERROR: This type is not a record type
let evt = CustomEvent.Create ("hello", details)
elem.dispatchEvent evt

Any help on how to achieve this would be greatly appreciated!

CustomEventInit is a class type, so you can instantiate it using an object expression:

let details =
    let mutable bubbles = true
    let mutable cancelable = true
    let mutable composed = true
    let mutable detail : obj = "John"
    {
        new CustomEventInit with
            member _.bubbles
                with set(value) = bubbles <- value
                and get() = bubbles
            member _.cancelable
                with set(value) = cancelable <- value
                and get() = cancelable
            member _.composed
                with set(value) = bubbles <- value
                and get() = bubbles
            member _.detail
                with set(value) = detail <- value
                and get() = detail
    }

Or you could create a named subclass if you prefer.