打字稿/反应：模块没有导出成员

Question

I am trying to export prop types from one view component to another container component and use them as state type definitions:

// ./Component.tsx
export type Props {
    someProp: string;
}

export const Component = (props: Props ) => {
    ...etc
}

// ./AnotherComponent.tsx
import { Component, Props as ComponentProps } from "./Component";

type Props = {}

type State = ComponentProps & {};

class AnotherComponent extends React.Component<Props, State> {
    state: State;
    ...etc
}

However I am getting in console:

Module '"./Component "' has no exported member 'Props'.

Any suggestions for how I should be going about this?

I have also tried using lookup types as per this article, but no joy.

Answer 1

Try something like this. Basically extend the component Props, to include your desired import.

export interface IProps extends PropsOfYouChoiceThatYouImport {
 morePropsHere
}

Also do not include Props into State it is completly wrong IMO. Do something like this:

interface IProps extends YourDesiredProps {
  someProp: string | null;
  // etc
}

interface IState {
  something: boolean
  // etc
}

export class ComponentName extends Component<IProps, IState> {
  // Define you state, and props here. You need to initialize the correct IState 
  // and IProps above
}

As for the console error, I am not sure you can do that.Try create a folder called Types or Interfaces . Then export that one.

And import it as named or default export, whatever you wish, at both files. Since you want to reuse it. Tell me if it helps. I can look more into it, if you make a quick codeSandbox..

Basically what I suggest is put this into a separate file:

export type Props {
    someProp: string;
}

Answer 2

If you check the React typings ( node_modules/react/index.d.ts ) of React.Component the structure is the following:

class Component<P, S> {...}

where P equal props and S means state. You should not mix props and state.

To fix your TypeScript error change type to interface :

export interface Props {
  someProp: string;
}

Answer 3

The issue for the missing member export was the fact that I had an intermediary index file which TypeScript doesn't seem to be able to use when exporting types:

// ./Component/index.tsx
export { Component, Props } from "./js/Component";

When I change the import to use an exact path to the file rather than trying to import it through the index file it picked it up:

// ./AnotherComponent/js/AnotherComponent.tsx
import { Props as ComponentProps} from "./Component/js/Component";