Input mask provides a general format to text field and enforces its structure as the user typing in values. It provides the user an idea about how they should enter the data. Use set_mask() method to mask any text input.
phpDatabaseForm uses an excellent jQuery Mask Input created by Igor Escobar available distributed under MIT license.
// ... code omitted
$dbForm -> load_form(9);
$dbForm -> redirect_after_submit("http://example.com");
$dbForm -> set_mask("HomePhone", "(000)000-0000", "{placeholder: '(___)__-____'}");
$dbForm -> display();
$dbForm -> load_form(9);
$dbForm -> redirect_after_submit("http://example.com");
$dbForm -> set_mask("HomePhone", "(000)000-0000", "{placeholder: '(___)__-____'}");
$dbForm -> display();