How to iterate through nested objects in JS

Question

Ok I\'m stumped on this one. I need to iterate through these so I can make a listing by the category so something like

Business Books

Book 1

Answer 1

jQuery.each(window.books, function(category, items) {
    alert(category);

    jQuery.each(items, function(idx, book) {
        alert(category + ': ' + book.Title)
    });
});