Мемоизация №1

function memoize(fn, timeout) {
    let cache = null;
    let expire = Date.now() + timeout;

    return function() {
        if (!cache || Date.now() > expire) {
            return fn().then(data => {
                cache = data;
                expire = Date.now() + timeout;
                return data;
            });
        }

        return Promise.resolve(cache);
    }
}