I am trying to figure out how the AjaxUniqueTextField work, the form class has the following ajaxuniquetextfield:
AjaxUniqueTextField::create('Username', 'Username*', "Username", "account", "", 16, "validate", "^[a-zA-Z0-9]+$^")
As far as I know it has the following parameter:
$value = "",
$maxLength = null,
$validationURL = null,
$restrictedRegex = null
If you have an example of a working version, would you mind sharing it?