typescript-cheatsheets/react

If your components Props interface extends another interface, defaultProps still doesn't work in TS3

gausie opened this issue · 12 comments

gausie commented
If your components Props interface extends another interface, defaultProps still doesn't work in TS3
swyxio commented

ok what do you recommend i put in the cheatsheet?

gausie commented
swyxio commented

have you reported this as a bug? (is this a bug? i think it is?)

gausie commented
swyxio commented

just try :) good luck

ferdaber commented

Do you have a code example for this? I would also open this as an issue in the DefinitelyTyped repo instead so the other React types maintainers can take a look.

infctr commented

I guess it goes like

type ComponentProps<T> = T extends React.ComponentType<infer P> | React.Component<infer P>
  ? JSX.LibraryManagedAttributes<T, P>
  : never;

interface IProps {
  name: string;
}

interface IDefaultProps {
  age: number;
}

const GreetComponent = ({ name, age }: IProps & IDefaultProps) => (
  <div>{`Hello, my name is ${name}, ${age}`}</div>
);

const defaultProps: IDefaultProps = {
  age: 25,
};

GreetComponent.defaultProps = defaultProps;

// later

const TestComponent = (props: ComponentProps<typeof GreetComponent>) => {
  return (
    <div> <h1 /> </div>
  );
};

const el = <TestComponent name="foo" />;
  • 👍6
  • 🎉2
swyxio commented

thanks for the input @infctr! i dont quite see the point of TestComponent.

  • if i replace your impl of ComponentProps with the official one React.ComponentProps, i see that TestComponent errors because of the missing age default prop.
  • if i then add TestComponent.defaultProps = defaultProps; it typechecks.

this seems correct behavior.

@gausie, can we please see an example that you expect to work? otherwise its very hard to discuss.

infctr commented

@sw-yx My point is (and that's my understanding of @gausie problem)

type Props = React.ComponentProps(typeof GreetComponent) // all props are required

type Props = ComponentProps<typeof GreetComponent> // using helper, defaulted props are optional

Extracting props with JSX.LibraryManagedAttributes is more in line with the old practice marking default props as optional on an interface like interface Props extends Partial<DefaultProps> { /* ... */ } and using it later.

Consdider this

interface Props extends ComponentProps<typeof GreetComponent> {
  title: string;
}

const TestComponent = ({ title, ...props }: Props) => {
  return (
    <>
      <h1>{title}</h1>
      <GreetComponent {...props} />
    </>
  );
};

// age is optional on an inner component's props interface
const el = <TestComponent name="Johnny 5" title="foo" />;

Just thought it was worth mentioning as it was not immediately obvious

  • 👍2
ferdaber commented

That's correct. There are valid use cases for extracting both the inner props of a component, or the apparent props (with JSX.LibraryManagedAttributes). The built-in React types only take care of the first case.

swyxio commented

hoo boy. ok. thank you

stale commented

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions!