Dynamic return type of object properties using TypeScript-CodePudding

I have a function that receive an object and return an object of methods with the same property names:

function someGenerator<P extends {}>(params: P) {
  return Object.keys(params).reduce((acc, key) => ({
    ...acc,
    [key]: () => {
      console.log(params[key]);
    },
  }), {});
}

Basically I want to use it like so:

type Params = {
  str: string;
}

const params = {
  str: 'some text',
}

const someInstance = someGenerator<Params>(params);

someInstance.str();

I tried to define the return type of that function:

type ReturnType<P> = {
  [K in keyof P]: () => void;
}

But this type doesn't work as I expected, because the definition of the return type does not hold the params like it should.

Can anyone help with define the return type?

CodePudding user response：

.reduce inferred types will be usually be defined as the accumulator's start value. I usually end up doing this when I have a function that returns a reduced value:

function someGenerator<P extends Record<string, any>>(params: P) {
  return Object.keys(params).reduce(
    (acc, key) => ({
      ...acc,
      [key]: () => {
        console.log(params[key]);
      }
    }),
    {} as Record<keyof P, () => void>
  );
}