async_await.js

 function addTvShowToDb(tmdbId) {
        return new Promise(async (resolve, reject) => {
            try {
                const res = await getTv(tmdbId);
                const tv = {
                    tmdb_id: res.id,
                    overview: res.overview,
                    genres: res.genres,
                    seasons: res.seasons,
                    created_by: res.created_by,
                    title: res.name || res.original_name,
                    poster_path: res.poster_path,
                    backdrop_path: res.backdrop_path,
                    first_air_date: res.first_air_date,
                    vote_average: res.vote_average,
                    status: res.status
                };
                if (res.videos && res.videos.results && res.videos.results.length > 0) {
                    tv.videos = res.videos.results;
                    tv.trailer_key = res.videos.results[0].key;
                }
                if (tv.seasons) {
                    const seasons = await getSessonDetails(tv.tmdb_id, tv.seasons);
                    tv.seasons = seasons.map(season => {
                        return {
                            id: season.id,
                            air_date: season.air_date,
                            poster_path: season.poster_path,
                            overview: season.overview,
                            season_number: season.season_number,
                            name: season.name
                        };
                    });
                    const addedTv = await TvShow.create(tv);

                    const episodes = seasons.map(season => {
                        return season.episodes;
                    })
                    .reduce((prev, curr) => { return prev.concat(curr) }, [])
                    .map(episode => {
                        return {
                            tvId: tv.tmdb_id,
                            air_date: episode.air_date,
                            episode_number: episode.episode_number,
                            title: episode.name,
                            overview: episode.overview,
                            tmdb_id: episode.id,
                            season_number: episode.season_number,
                            still_path: episode.still_path,
                            vote_average: episode.vote_average,
                        }
                    });
                    await addEpisodes(episodes);
                    resolve(addedTv);
                }
                else {
                    throw makerError(Util.UNKNOWN_ERROR);
                }
            } catch (err) {
                reject(err);
            }

        });
    }