Modern Front-End Development for Rails, 2nd Edition

Lazy Loading a Turbo Frame

Let’s stretch this a little. Let’s add one more feature: a count of the number of favorited items in the header. You can think of this as being broadly analogous to a shopping cart. And along the way, I’ll show you one more Turbo feature: lazy loading.

Lazy loading allows us to separate the static and dynamic parts of a page so that the static part can be cached and the dynamic part automatically fills itself in when the page is loaded. If the dynamic part is slow, then this technique can also make the rest of the page appear faster and give the user a loading sign or something while the slow part of the page catches up.

To make this work, we want an entry in the navigation bar that is a placeholder for the favorites ...