forms

I needed to redirect the user register form based on a role that the user wanted to apply for.

Adding placeholder text to a Drupal 8 form element that is the label of the form can be done in your .theme file with the hook template_preprocess_input().

/**
 * Implements template_preprocess_input().
 */
function MYTHEME_preprocess_input(&$variables) {
  // Set a placeholder for all search form elements.
  if ($