在Typescript中获取泛型类型的内部类型

Question

如何在Typescript中获取泛型类型的内部类型？那么myType<T>的T呢？

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, ... }'?

感谢

Answer 1

您可以使用infer关键字从泛型类型中获取类型参数。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, ... }