service

insertNewRating(newRating:Rating):Observable<Rating>{
        let max:number = Math.max.apply(Math, ratings.map( rating => rating.id))
        let newId:number = max + 1

        let description = Object.getOwnPropertyDescriptor(ratings, "length");
        console.log('is array writable?', description.writable)

        ratings.push({id:newId, itemId:newRating.itemId, rating:newRating.rating})

        return of(newRating)
    }