Answers for "show items on a form if checkbox checked"

if checkbox is checked

if ($('#id_input').is(':checked')) { }

if checkbox is checked open forms

<div class="form-group" id="checkbox">
        <%= f.check_box :paydeliver %>
        <%= f.label :paydeliver, "Pay $25" %>
      </div>

      <div id="delivery" style="display:none;">
        <div class="form-group">
          <%= f.label :addysdeliver, "Delivery address"%>
          <%= f.text_field :addysdeliver, class: "form-control"%>
        </div>
      </div>

      <%= f.submit "Go!", class: "btn btn-primary btn-large btn-block" %>

      <% end %> #end of form