input[type="number"] to spinner

.js

function quantityInput() {
   $('<div class="quantity-button quantity-up">+</div><div class="quantity-button quantity-down">-</div>').insertAfter('.quantity input[type="number"]');
   $('.quantity').each(function() {
      var spinner = $(this),
         input = spinner.find('input[type="number"]'),
         btnUp = spinner.find('.quantity-up'),
         btnDown = spinner.find('.quantity-down'),
         min = input.attr('min'),
         max = input.attr('max');
      
      btnUp.click(function() {
         var oldValue = parseFloat(input.val());
         if(max!=''){
            if (oldValue < max) {
               var newVal = oldValue + 1;
               spinner.find("input").val(newVal);
               spinner.find("input").trigger("change");
            } else {
               var newVal = oldValue;
            }
         } else {
            var newVal = oldValue + 1;
            spinner.find("input").val(newVal);
            spinner.find("input").trigger("change");
         }
         
         
      });

      btnDown.click(function() {
         var oldValue = parseFloat(input.val());
         if(min!='') {
            if (oldValue <= min) {
               var newVal = oldValue;
            } else {
               var newVal = oldValue - 1;
               spinner.find("input").val(newVal);
               spinner.find("input").trigger("change");
            }
         } else {
            var newVal = oldValue - 1;
            spinner.find("input").val(newVal);
            spinner.find("input").trigger("change");
         }
         
      });

   });
}