This illustrates how the Moodle autocomplete form element can be used. The sample data is alpha,bravo,charlie etc. The source can be found here https://github.com/marcusgreen/moodle-local_autocomplete2 The documentation for the autocomplete element can be found at https://docs.moodle.org/dev/lib/formslib.php_Form_Definition#autocomplete

options = array ( 'multiple' => false, 'tags' => false, 'placeholder' => '', 'casesensitive' => '', 'noselectionstring' => '', 'showsuggestions' => true, )

multiple