$('#demo3').click(function(){
       selectedDraggable.circleType($(this).val());
         });

         <button id="demo3">Curve</button>

        $('#demo2').click(function(){
         selectedDraggable.circleType({radius: 384,     dir:-1});
         });

         <button id="demo2">Curve</button>




         <script src="https://code.jquery.com/jquery-1.12.3.min.js"></script>
         <!--
        <script src="https://. circletype.labwire.ca/js/circletype.js"></script>
        <script src="https://tympanus.net/Development/Arctext/js/jquery.arctext.js"></. script>