title: Change total sum when change quantity
body: <p>I have such html</p>
  
  <pre><code>&lt;td class="cart_price"&gt;
      &lt;p class="price_jq"&gt;11&lt;/p&gt;
  &lt;/td&gt;
  &lt;td class="cart_quantity"&gt;
      &lt;input type='button' value='-' class='qtyminus' field='quantity' /&gt;
      &lt;input type='text' name='quantity' value='1' class='qty' /&gt;
      &lt;input type='button' value='+' class='qtyplus' field='quantity' /&gt;
  &lt;/td&gt;
  &lt;td class="cart_total"&gt;
       &lt;p class="cart_total_price"&gt;&lt;/p&gt;
   &lt;/td&gt;
  </code></pre>
  
  <p>And such jquery scripts</p>
  
  <pre><code>$(document).ready(function(){
          $('.qtyplus').click(function(e){
              e.preventDefault();
              fieldName = $(this).attr('field');
              var currentVal = parseInt($('input[name='+fieldName+']').val());
              if (!isNaN(currentVal)) {
                  $('input[name='+fieldName+']').val(currentVal + 1);
              } else {
                  $('input[name='+fieldName+']').val(0);
              }
          });
          $(".qtyminus").click(function(e) {
              e.preventDefault();
              fieldName = $(this).attr('field');
              var currentVal = parseInt($('input[name='+fieldName+']').val());
              if (!isNaN(currentVal) &amp;&amp; currentVal &gt; 0) {
                  $('input[name='+fieldName+']').val(currentVal - 1);
              } else {
                  $('input[name='+fieldName+']').val(0);
              }
          });
  
          var sum = 0;
          var total = 0;
          $('.price_jq').each(function () {
              var price = $(this);
              var count = price.closest('tr').find('.qty');
              sum = (price.html() * count.val());
              total = total + sum;
              price.closest('tr').find('.cart_total_price').append(sum + "₴");
          });
          $('#total').append("&lt;h3&gt;£" + total + "&lt;/h3&gt;");
      });
  </code></pre>
  
  <p>I think i must use Jquery change, but i try and in result i have nothing. Maybe i miss something</p>
  
  <p>I need when i update in td cart_quantity number, update my total price.</p>