Agile Web Development with Rails 5, 1st Edition

Iteration F2: Creating an Ajax-Based Cart

Ajax lets us write code that runs in the browser and interacts with our server-based application. In our case, we’d like to make the Add to Cart buttons invoke the server create action on the LineItems controller in the background. The server can then send down just the HTML for the cart, and we can replace the cart in the sidebar with the server’s updates.

Now, normally we’d do this by writing JavaScript that runs in the browser and by writing server-side code that communicates with this JavaScript (possibly using a technology such as JavaScript Object Notation [JSON]). The good news is that, with Rails, all this is hidden from us. We can use Ruby to do everything we need to do (and with a whole lot ...