Modal dialogs are great and provide a great experience for the end user - they allow for quick display of content in an overlay without navigating to another page. Getting forms to load and render properly in a modal can sometimes be a little tricky, but fortunately, it’s relatively straightforward to implement in Drupal 8.

We will be setting up a custom form containing a button that opens up another form in a modal using Drupal’s FormBuilder and AJAX API. So, let’s get started!