TYPESCRIPT

typescript returntype remove promise

type UnPromisifiedObject<T> = {[k in keyof T]: UnPromisify<T[k]>}
type UnPromisify<T> = T extends Promise<infer U> ? U : T;

async function promise_props<T extends {[key: string]: Promise<any>}>(obj: T): Promise<UnPromisifiedObject<T>> {
    const keys = Object.keys(obj);
    const awaitables = keys.map(key => obj[key]);

    const values = await Promise.all(awaitables);
    const result = {} as any;

    keys.forEach((key, i) => {
        result[key] = values[i];
    });
    return result as UnPromisifiedObject<T>;
}

async function main() {
    const x = {
        company: Promise.resolve("company"),
        page: Promise.resolve(1)
    };
    const res = await promise_props(x);
    const company = res.company;  // company is a string here
    const page = res.page;        // page is a number here
}