example.html.erb

<%= vpi_button_to_function @readonly ? "Close" : "Cancel", cancel_js, :class => 'vpi_submit_button' %>

<%= button_to @readonly ?  "Close" : "Cancel", class: 'vpi_submit_button', data: {function: "cancel-js"} %>

<% cancel_js = data_set.new_record? ? "$('##{data_set_row_id}').remove();" : "toggle_data_set('#{data_set.id}', '#{builder_id}', '#{data_set_row_id}'); return false;"%>