在打字稿中获取通用类型的内部类型

Question

如何在Typescript中获得泛型类型的内部类型？那么T的myType<T>？

例如：

export class MyClass {
  myMethod(): Observable<{ prop1: string, ... }> {
    ....
  }
}

type myClassReturn = ReturnType<MyClass['myMethod']>;
// Sets the type to 'Observable<{ prop1: string, ... }>'. 
// How do I set this to just '{ prop1: string, ... }'?

谢谢

Answer 1

您可以使用infer关键字以从通用类型获取类型参数。考虑：

type GetInsideObservable<X> = X extends Observable<infer I> ? I : never;

// in your case it would be:
type A = GetInsideObservable<ReturnType<MyClass['myMethod']>> // { prop1: string, ... }