reactjs - How do I restrict the type of React Children in TypeScript, using the newly added support in TypeScript 2.3?

Question

I'm trying to take advantage of the recently added support for typing of children in the TypeScript compiler and @types/react, but struggling. I'm using TypeScript version 2.3.4.

Say I have code like this:

interface TabbedViewProps {children?: Tab[]}
export class TabbedView extends React.Component<TabbedViewProps, undefined> {

  render(): JSX.Element {
    return <div>TabbedView</div>;
  }
}

interface TabProps {name: string}
export class Tab extends React.Component<TabProps, undefined> {
  render(): JSX.Element {
    return <div>Tab</div>
  }
}

When I try to use these components like so:

return <TabbedView>
  <Tab name="Creatures">
    <div>Creatures!</div>
  </Tab>
  <Tab name="Combat">
    <div>Combat!</div>
  </Tab>
</TabbedView>;

I get an error as follows:

ERROR in ./src/typescript/PlayerView.tsx
(27,12): error TS2322: Type '{ children: Element[]; }' is not assignable to type 'IntrinsicAttributes & IntrinsicClassAttributes<TabbedView> & Readonly<{ children?: ReactNode; }> ...'.
  Type '{ children: Element[]; }' is not assignable to type 'Readonly<TabbedViewProps>'.
    Types of property 'children' are incompatible.
      Type 'Element[]' is not assignable to type 'Tab[] | undefined'.
        Type 'Element[]' is not assignable to type 'Tab[]'.
          Type 'Element' is not assignable to type 'Tab'.
            Property 'render' is missing in type 'Element'.

It seems to be inferring the type of children as just Element[] instead of Tab[] even though that's the only type of children I'm using.

EDIT: It would also be fine to restrict the interface of the children props instead of restricting the type of the children components directly, since all I need to do is pull some specific props out of the children components.

Answer 1

Edit 2: Turns out that this approach prevent the warning, but according to the comments TabProps aren't properly checked.

You should try to set children of interface TabbedViewProps like so

interface TabbedViewProps { children?: React.ReactElement<TabProps>[] }

The idea here is not to tell your TabbedView has an array of Tab, but instead tell your TabbedView he has an array of element which takes specific props. In your case TabProps.

Edit ( thx to Matei ):

interface TabbedViewProps {
    children?: React.ReactElement<TabProps>[] | React.ReactElement<TabProps>
}