promisifyAll

promisify.ts

type CallbackBasedAsyncFunction<T> = (callback: (response: ApiResponse<T>) => void) => void;
type PromiseBasedAsyncFunction<T> = () => Promise<T>;

export function promisify<T>(fn: CallbackBasedAsyncFunction<T>): PromiseBasedAsyncFunction<T> {
    return () => new Promise<T>((resolve, reject) => {
        fn((response) => {
            if (response.status === 'success') {
                resolve(response.data);
            } else {
                reject(new Error(response.error));
            }
        });
    });
}

type SourceObject<T> = {[K in keyof T]: CallbackBasedAsyncFunction<T[K]>};
type PromisifiedObject<T> = {[K in keyof T]: PromiseBasedAsyncFunction<T[K]>};

export function promisifyAll<T extends {[key: string]: any}>(obj: SourceObject<T>): PromisifiedObject<T> {
    const result: Partial<PromisifiedObject<T>> = {};
    for (const key of Object.keys(obj) as (keyof T)[]) {
        result[key] = promisify(obj[key]);
    }
    return result as PromisifiedObject<T>;
}