This is project specific code, just for record.

Reflect flexslider image on shopify product page

 <script type="text/javascript">

    
function Imagw(thisvalue) {  
   var slideshow = $('#slider-product-template-2');
            theme.slideshows[slideshow] = new theme.Slideshow(slideshow);
            //  slideshow.flexslider(6);
            var $newImgs = slideshow.find(
                '.slide[data-img-alt="' + thisvalue + '"]'
            );
            slideshow.find('.slide').removeClass('rt');
            $newImgs.addClass('rt');
            var index = slideshow.find('.rt:eq(1)').attr('data-index');
            slideshow.flexslider(parseInt(index));
            var index_array = []
            slideshow.find('.slide').not('.rt').each(function() {
                index_array.push($(this).attr('data-index'));
            });
            $('.flex-control-thumbs > li').removeClass('rt1');
            $.each(index_array, function(index, value) {
                $('.flex-control-thumbs').find('li:eq(' + parseInt(value) + ')').addClass('rt1');
            });
            theme.slideshows[slideshow] = new theme.Slideshow(slideshow);
            $('.flex-control-thumbs > li').show();
            $('.flex-control-thumbs').find('li:eq(0)').hide();
            $('.rt1').hide();
}  
    
    
    $(function() {


        $(document).on('change', 'select', function() {
            var thisvalue = $(this).find("option:selected").text();
          if(thisvalue == "Vanilla" || thisvalue == "Chocolate"){
             Imagw(thisvalue)
          }
	       
        });
      

      
      $(".tab button").click(function(){
            var radioValue = $(this).find("input[name='sele']:checked").val();

        
        if(radioValue == "one-time-purchase"){
//         alert("one-time-purchase");
          var text = $('.'+radioValue).find(".jumpstart-selector select option:selected").text();  
          Imagw(text);
        }
        else if(radioValue == "monthly-subscription"){
//         alert("monthly-subscription");
           var text = $('.'+radioValue).find(".jumpstart-selector select.single-option-selector option:selected").text();  
          Imagw(text);
        
        }
        
        });
      
      

    });
</script>