It's not a good idea to have numbers as keys in your object lists

[Razpudding]

Since you cant rely on the order keys in an object are stored, these numbers are kind of meaningless right now.
It would be better to have the title as a key.

[Razpudding]

Another reason for this is that now your ids in html are also meaningless "1,2,3," they dont tell you anything. Would be a lot better if these were the names of the books.