af/form/previous_button_atts
Filter attributes on the previous button in multi-page forms. Use to add classes, set an ID, or add new attributes.
$attributes
is an array of HTML attributes and their values.
<?php
function filter_previous_button_attributes( $attributes, $field ) {
$attributes['class'] .= ' button';
return $attributes;
}
add_filter( 'af/form/previous_button_atts', 'filter_previous_button_attributes', 10, 2 );