I have a list of books and I want to store data against each book e.g. Price, Quantity, id, catergory id, size, weight etc.
I was looking at storing all this in the
The choice is really dependant on your application architecture and type of functionality in your application. If you are building a single page app I found that using a well constructed json object in conjunction with a good templating plugin gives you much more flexibility in terms of functionality.
I found that indexing your data on an id in your json and then storing that id in the "data-" element gives you a nice way of reacting to browser events (clicks etc) without having to search through JSON structure. Having a JSON structure also makes it a bit easier to do operations such as sorting lists and other global operations that you might want to do without having to rebuild your data from DOM. This method is also better when you work with MVC like frameworks or implement your own "observable" data structures.
On the other hand if you are working with mostly server side code and have only basic functionality in your page that utilizes your "data-" data (such as display book details on click or something simple like that), it is probably simpler to just use the "data-" attribute to store additional details.