However, while this is stopping my custom validation code from running, it isn't stopping built-in validation for fields that I defined as required in the Drupal interface.The as recommended here, but this just refreshed the form without showing validation errors instead of redirecting where I want it to go, so I have no idea what this code is actually doing or if this is even applicable for Drupal 8. Then, in your Page class, you can choose which of these fields to include in the form.
You can build these interfaces in any front-end framework you want.
You do that in the 'Validation' section of a form element: Under most circumstances, you will want to choose a validation rule from the library.
To do so, click on the 'Library' radio button next to Validation (as shown above).
If you want them to be determined dynamically (e.g.
different from player to player), then you can instead define one of the below methods in your Let’s say you don’t want users to fill out form fields, but instead interact with some sort of visual app, like a clicking on a chart or playing a graphical game.