TypeScript: how to extract the generic parameter from a type?
Solution 1:
You can use infer:
type TypeWithGeneric<T> = T[]
type extractGeneric<Type> = Type extends TypeWithGeneric<infer X> ? X : never
type extracted = extractGeneric<TypeWithGeneric<number>>
// extracted === number
Playground
Solution 2:
You can use pattern matching for that:
namespace React {
export class ComponentClass<T> {}
}
function doSomethingWithProps<T>(x : React.ComponentClass<T>) : T {
return null as T;
}
class Something {}
let comp = new React.ComponentClass<Something>();
const instanceOfSomething = doSomethingWithProps(comp);