The simplest way to interact with Drupal's Ajax API is to add the class use-ajax to any link. This will cause the link to make an Ajax request to the path of the link rather than moving the browser to it. A similar thing can be done with the submit button of a form using the class use-ajax-submit. This makes the form submit via Ajax to the path defined in the form's action.
The most important thing, however, is what we do on the other end of the process. Clicking a link which triggers an Ajax request won't do anything if we don't handle that request accordingly. What we have to do is return an AjaxResponse object with some jQuery commands that instruct the browser on the changes it needs to make to the DOM. So, let's see an example. ...
