In what ways can elements of the general concept be inferred from incorporating TypeScript?

Question

In what ways can elements of the general concept be inferred from incorporating TypeScript?

I'm facing a challenge in figuring out how to achieve a specific task. We have a function called createActions that requires an object type and a string as a key.

function createActions<T, Tkey extends string>(key: Tkey) {
    return function(obj: T) {
        return {[key]: obj}
    }
}

My goal is to automatically infer the type of Tkey, while ensuring strong typing for T. The objective here is to enable developers to access defined properties in a properly typed manner. For instance, if the specified key is a, calling createActions('a')({}).b should trigger a compiler error since b is not part of type {a: {}}.

This concept is an extension of our existing implementation, which can be viewed at: https://github.com/CaliStyle/ngrx-poly/blob/master/src/app/ngrx-poly/actions/depth-one-action-map.ts. Any insights on how to tackle this challenge?

angular typescript

Answer 1

Answer №1

To achieve the desired inference, it is important to specify the type parameter at the appropriate level based on its parameter inference context.

function createActions<Tkey extends string>(key: Tkey) {
    return function<T>(obj: T) {
        return {[key]: obj};
    };
}

const createPerson = createActions('person');

const hasPerson = createPerson({name: 'Robert', id: 1});

console.log(hasPerson.person.name);

Playground link

Answer 2

To achieve the desired inference, it is important to specify the type parameter at the appropriate level based on its parameter inference context.

function createActions<Tkey extends string>(key: Tkey) {
    return function<T>(obj: T) {
        return {[key]: obj};
    };
}

const createPerson = createActions('person');

const hasPerson = createPerson({name: 'Robert', id: 1});

console.log(hasPerson.person.name);

Playground link

In what ways can elements of the general concept be inferred from incorporating TypeScript?

Answer №1

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