仅将 class 导出为 typescript 定义文件中的类型

Question

Suppose that you have an ES6 library named my-lib like this one

export class Foo {
   ...
   createBar() {
      return new Bar();
   }
   ...
}
class Bar() {
   method1() {}
   method2() {}
   method3() {}
}

and you have to write the typescript definitions for the above library like so.

export class Foo() {
    ...
    public createBar():Bar;
}
export class Bar() {
   method1(): void
   method2(): void
   method3(): void
}

My questions is: Should the Bar class be exported?

If yes then by writing the following code

import { Bar } from 'my-lib'

will lead to declaring a Bar variable which is undefined

If no, then the following statement will be incorrect, since Bar is not imported

const foo = new Foo()
const bar: Bar = foo.createBar();

How should I define the Bar class so that it is exported as a type and NOT as a class?

Answer 1

I am not sure if I understand what you're trying to achieve but if you don't want to expose your class directly but only its 'shape' (type) you can define it as an interface.

export class Foo {
    createBar(): IBar {
        return new Bar();
    }
}

class Bar {
    method1() { }
    method2() { return 'test'; }
    method3() { return true; }
}

export interface IBar {
    method1: () => void,
    method2: () => string,
    method3: () => boolean,
}

const foo = new Foo()
const bar: IBar = foo.createBar();

And then you import only Foo and IBar.