How to fetch only the array from the form elements javascript

I used like this

var fData = $('.my_form').serializeArray();

which was my formdata, which contains all the form inputs done by the user.

the output of serializeArray will look like this

1. name: ‘library[0][] ‘,value : ‘3’
2. name: ‘library[0][] ‘,value : ‘5’
3. name: ‘time’ , value: ‘2:30 PM’
4. name: ‘bookname’, value: ‘space mission’
5. name: ‘library[1][] ‘,value : ‘8’
6. name: ‘detail_days[0][]’, value: ‘3’
   .
   .

like this, i need only library array alone from it, how to fetch it?

library = >{ ‘0’ =>{‘3′,’5’}, ‘1’ =>{‘8′,’10’}
like this i need to access this specific array alone

is there anything like serializeArray, forgetting only the specific array