(Docs) getStaticProps & getServerSideProps TS section (#40607)

[sicikh]

Added examples to getStaticProps & getServerSideProps explicit and implicit typings for TypeScript.

Related issues: fixes #40607

[HaNdTriX]

Hey @sicikh thank you for working on improving the documentation 🙏.

From my point of view I don't recommend mixing the type GetServerSideProps and InferGetServerSidePropsType.
This is because the type GetServerSideProps explicitly tells typescript what getStaticProps will return. InferGetServerSidePropsType will infer these types instead of defining them. If you now use both InferGetServerSidePropsType will get the type from GetServerSideProps<T> instead of inferring it from js.

As you can see the last approach infers the correct types the first one uses a default type which is critical from my point of view.

The same applies to GetStaticProps. I am currently working on fixing InferGetServerSidePropsType types in #40635.

[sicikh]

Hey @sicikh thank you for working on improving the documentation 🙏.

From my point of view I don't recommend mixing the type GetServerSideProps and InferGetServerSidePropsType. This is because the type GetServerSideProps explicitly tells typescript what getStaticProps will return. InferGetServerSidePropsType will infer these types instead of defining them. If you now use both InferGetServerSidePropsType will get the type from GetServerSideProps<T> instead of inferring it from js.

As you can see the last approach infers the correct types the first one uses a default type which is critical from my point of view.

The same applies to GetStaticProps. I am currently working on fixing InferGetServerSidePropsType types in #40635.

Thanks for the reply! The problem given in your example is exactly what was missing in the existing documentation. The current behavior of types when we explicitly specify the type of functions is the standard behavior of TypeScript with type calculation. If we want to type the props in the page, while maintaining the explicit typing of getStaticProps, then we must give the types of the returned props in the generics of the function getStaticProps: GetStaticProps<{ propsObject: propsObjectType }>. Otherwise, InferGetStaticProps will type the props as [key:string]: any because of the following:

That is why it is necessary to specify two examples in the documentation, with an explicit and implicit specification of the type of function of data fetching.

[balazsorban44]

Thanks!

[leerob]

Will tsx work? I am unsure (worth checking)