resolveProps() function

Promise である可能性のあるオブジェクトのすべてのプロパティを解決します。

Signature:

declare function resolveProps<T extends object, Key = Exclude<keyof T, symbol>>(
  obj: T,
): Promise<{
  [K in keyof T]: K extends Key ? Awaited<T[K]> : never;
}>;

Example

const obj = {
  a: Promise.resolve(1),
  b: 2,
  c: Promise.resolve(3),
};

const result = await resolveProps(obj);
console.log(result); // { a: 1, b: 2, c: 3 }

Also, with this function, you can define asyncEvolve simply.

const asyncEvolve =
  <T extends object>(transformation: Transformation<T>) =>
  (obj: T) =>
    pipe(obj, evolve(transformation), resolveProps);

const a = await asyncEvolve({ a: async (a) => a + 1 })({ a: 1 });
console.log(a); // { a: 2 }

const resultByFormat = await asyncEvolve<Request>({
  foo: async (foo) => await fetch(`https://example.com/foo/${foo}`).json(),
  bar: async (bar) => await fetch(`https://example.com/bar/${bar}`).text(),
});
const result = await resultByFormat({ foo: "foo", bar: "bar" });

console.log({
  foo: result.foo,
  bar: result.bar,
});

see pipe and evolve.

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