I shouldn't have to prepend my eventnames with "top"

[namrog84]

ConstantProviderDelegate SomeViewManager::ExportedCustomDirectEventTypeConstants() noexcept
{
    return [](winrt::Microsoft::ReactNative::IJSValueWriter const& constantWriter) {
        WriteCustomDirectEventTypeConstant(constantWriter, "Foo");
}
...
 ReactContext().DispatchEvent(someView, L"topFoo", args);

Most of our code is built around some constants in the class (e.g. SomeViewManager::Foo) instead of using literals everywhere.
Which means I need to do things like
winrt::to_hstring(std::string("top") + eventName);

It used to work without having to manually add "top", the internal DispatchEvent should handle these types of things or have appropriate functions to call like DispatchTopEvent

Even in the SampleApp
they are using "topLabelChanged" and "LabelChanged"

Also in places like this

https://github.com/react-native-community/react-native-video/blob/91384d848953d8c8b526a10f45d44f1bd38c62f0/windows/ReactNativeVideoCPP/ReactVideoView.cpp#L103
where Load, End, Seek, Progress were the registered names, but then someone had to fire "topLoad", "topEnd", "topSeek", and "topProgress"

[NickGerleman]

Jon Thysell (@jonthysell) Vladimir Morozov (@vmoroz)

[chrisglein]

Andrew suspects this is part of our code gen for view mangers and events.

[acoates-ms]

top prefix is hard coded here...

react-native-windows/vnext/Microsoft.ReactNative.Cxx/JSValueWriter.h

Line 211 in b602feb

WriteCustomDirectEventTypeConstant(writer, L"top" + eventName, L"on" + eventName);

[namrog84]

Also just as a FYI. We had discovered some weirdness from android to ios

Android can be anything and matches in all 3 (registration, in typescript, and on the call event).
iOS register and call "Name" but the typescript has to be "onName" because it looks like they prepend 1 area with "on"

So there is some inconsistency across all 3 platforms. Id personally vote for the android style of having the register, the call, and the javascript side all be the same.

I am okay with anything so long as I can use the same constant in c++ (register and call event)

[namrog84]

It looks like in the iOS implementation they have a helper function to optionally add it if its not already there and use it in a variety of places.

https://github.com/facebook/react-native/blob/aee88b6843cea63d6aa0b5879ad6ef9da4701846/React/Base/RCTEventDispatcher.m#L19

[namrog84]

Just want to point out. Depending on how a fix is implemented, the longer this persists, the more modules out in the wild will be implementing events and other stuff in ways that could potentially break with newer updates causing upgrade pains. And its not a particularly fun/easy bug to figure out if you don't have the tribal knowledge of having to if some underlying behavior changes.

The current behavior isn't aligned with how it behaves compared to RN on android and ios.

Register with "Name", call with "topName" and have javascript of "onName"