[@types/react] Preserve generic type parameters for component when passed to "lazy" or "memo"

[KurtGokhan]

forwardRef is going to be unnecessary in React 19 and it made the community happy. One of the reasons forwardRef is disliked is because it doesn't preserve generic type parameters of a component. Suppose a component like this:

function MyCmp<T extends ReactNode>({ value }: { value: T }) {
  return <>{value}</>;
}

When this component is wrapped in a HOC like forwardRef, memo or lazy, the component loses the generic ability.

See this behavior in TS playground.

Proposed solution

The culprit is the ExoticComponent type. It converts any component to a simple component like (props: P) => ReactNode without preserving the generic type parameters.

There is a simple solution to this issue. See a POC of the proposed solution giving off the expected behavior in TS playground. My POC doesn't consider class components though. If I get a green-light, I can make a reasonably backward-compatible solution.

Related discussions

See also #69029

[typescript-bot]

Thanks for the discussion about "react", some useful links for everyone:

• npm
• DT
• Related discussions

Pinging the DT module owners: @johnnyreilly, @bbenezech, @pzavolinsky, @ericanderson, @DovydasNavickas, @theruther4d, @guilhermehubner, @ferdaber, @jrakotoharisoa, @pascaloliv, @Hotell, @franklixuefei, @Jessidhia, @saranshkataria, @lukyth, @eps1lon, @zieka, @dancerphil, @dimitropoulos, @disjukr, @vhfmag, @hellatan, @priyanshurav, @Semigradsky, @mattpocock.

[KurtGokhan]

@eps1lon tagging you since you seem to be actively working on types. Any thoughts about this? Is there a plan to improve these types for React 19?

[eps1lon]

Not from me, no.