在扩展 EventEmitter 的 TypeScript 类中声明事件 [英] Declaring events in a TypeScript class which extends EventEmitter

问题描述

我有一个扩展 EventEmitter 的类，它可以发出事件 hello.如何使用特定的事件名称和侦听器签名声明 on 方法?

I have a class extends EventEmitter that can emit event hello. How can I declare the on method with specific event name and listener signature?

class MyClass extends events.EventEmitter {

  emitHello(name: string): void {
    this.emit('hello', name);
  }

  // compile error on below line
  on(event: 'hello', listener: (name: string) => void): this;
}

推荐答案

最有用的方法是使用declare:

declare interface MyClass {
    on(event: 'hello', listener: (name: string) => void): this;
    on(event: string, listener: Function): this;
}

class MyClass extends events.EventEmitter {
    emitHello(name: string): void {
        this.emit('hello', name);
    }
}

请注意，如果您要导出您的类，接口和类都必须使用 export 关键字声明.

Note that if you are exporting your class, both the interface and class have to be declared with the export keyword.

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