Filter object keys based on type

[maxludovicohofer]

TypeScript Version: 3.9

Search Terms:
Mapped types
Infer specific value of mapped type

Code

//? This type should be a map between keys of state (S) and keys of model (M)
//! A single mapping (key-value pair) should be possible only if 
//! the state property (S[P]) and the model property (M[specific keyof M]) are of the same type
type Wiring<S extends object, M extends object> = {
  [P in keyof S]?: S[P] extends M[keyof M] ? keyof M : never;
};

// Concrete example of state
type State = {
  dogNose: string;
};

// Concrete example of model
type Model = {
  earColor: string;
  hairColor: string;
  nose: string;
};

// Concrete example of wiring
const wiring: Wiring<State, Model> = { dogNose: "nose" }

Expected behavior:
What I would need is something along the lines of:

type Wiring<S extends object, M extends object> = {
  [P in keyof S]?: M[K in keyof M] extends S[P] ? K : never;
};

Basically, I would need to extract the keys K of M that extend the type of S[P] (note the M[K in keyof M]).
Is this possible?

[jcalz]

Questions like this do not belong here; try asking on Stack Overflow instead.

[typescript-bot]

This issue has been marked as 'Question' and has seen no recent activity. It has been automatically closed for house-keeping purposes. If you're still waiting on a response, questions are usually better suited to stackoverflow.