Typically you would place the books array somewhere that it can be easily accessed. What used to be done is to make it a global array, but that's not a good practice these days after we learn that globals should be kept to an absolute minimum, so a good place to store the array is as a property on the form that you use to to enter the information.
Originally Posted by jamesy23
var form = document.getElementById('bookSale');
form.books = ;