Javascript TypeScript-从对象创建联合

我正在用typescript创建EventEmitter，但我想不出一种方法来执行以下操作：

假设我有这样一个界面：

interface EventEmitterSubscription { dispose(): void }

// here it is
interface EventEmitter<T extends { [key: string]: any }> {
  onAnyEvent(callback: (event: { type: ???, payload: ??? }) => void): EventEmitterSubscription
  // ...
}

EventEmitter<{ onNumberReceived: number, onCatReceived: { cat: ICat }, onPersonNameReceived: string }>

type EventTypeMap<T extends { [key: string]: {} }> =
    { [K in keyof T]: { type: K; payload: T[K] } };

onAnyEvent字段的类型为

onAnyEvent(callback: (event: { type: 'onNumberReceived', payload: number } | { type: 'onCatReceived', payload: { cat: ICat } } | { type: 'onPersonNameReceived', payload: string }) => void): EventEmitterSubscription

目前，我的实现的界面如下所示：

onAnyEvent(callback: (event: { type: keyof T, payload: T[keyof T] }) => void): EventEmitterSubscription

除了当前不起作用之外，例如，它将生成类型

onAnyEvent（回调：（事件：{type:'onNumberReceived'，负载：number}{
键入：“onNumberReceived”，有效负载：{cat:ICat}}|/*…*/）=>void:EventEmitterSubscription

---

那么，我如何键入onAnyEvent字段？

创建联合的一种可能方法是使用映射类型，每个属性都具有所需联合的一个元素的类型，如下所示：

interface EventEmitterSubscription { dispose(): void }

// here it is
interface EventEmitter<T extends { [key: string]: any }> {
  onAnyEvent(callback: (event: { type: ???, payload: ??? }) => void): EventEmitterSubscription
  // ...
}

EventEmitter<{ onNumberReceived: number, onCatReceived: { cat: ICat }, onPersonNameReceived: string }>

type EventTypeMap<T extends { [key: string]: {} }> =
    { [K in keyof T]: { type: K; payload: T[K] } };

type EventTypeMap=
{[K in keyof T]：{type:K；payload:T[K]}；

然后可以定义泛型联合类型

type CallbackEventTypes<T extends { [key: string]: {} }> =
     EventTypeMap<T>[keyof EventTypeMap<T>] 

type CallbackEventTypes=
EventTypeMap[keyof EventTypeMap]

并使用它

interface EventEmitterSubscription { dispose(): void }

interface EventEmitter<T extends { [key: string]: {} }> {
  onAnyEvent(callback: (event: CallbackEventTypes<T>) => void): EventEmitterSubscription
  // ...
}

interface ICat { meow() }

type Emitter = EventEmitter<{ onNumberReceived: number, onCatReceived: { cat: ICat }, onPersonNameReceived: string }>

type HandlerType = Emitter['onAnyEvent'];

// inferred as
//type HandlerType = 
// (callback: (event: { type: "onNumberReceived"; payload: number; }
//                  | { type: "onCatReceived"; payload: { cat: ICat; }; }
//                  | { type: "onPersonNameReceived"; payload: string; }
//            ) => void) => EventEmitterSubscription

接口EventEmitterSubscription{dispose（）：void}
接口事件发射器{
onAnyEvent（回调：（事件：CallbackEventTypes）=>void）：EventEmitterSubscription
// ...
}
接口ICat{meow（）}
类型发射器=事件发射器
类型HandlerType=发射器['onAnyEvent']；
//推断为
//类型HandlerType=
//（回调：（事件：{type:“onNumberReceived”；负载：number；}
//|{type:“onCatReceived”；有效负载：{cat:ICat；}；}
//|{type:“onPersonNameReceived”；有效负载：string；}
//）=>void=>EventEmitterSubscription

这正是我要找的！杰出的