title: .on change function works first time not second?
body: <p>I have a shopping cart that calculates cost and shipping based on quantity and weight. Because of this there are two possible shipping options and I have a function to auto-select the correct shipping on page load. However, if a person changes the quantity the function to select the shipping must run again. </p>
  
  <p>To do this I tried this code: </p>
  
  <pre><code>$('.cartInputText').on('change', function() {   
      $('#ShippingOptions option').each(function(){
          if (this.value == '163182') {
              $('#ShippingOptions option[value="163182"]').prop('selected', true)
              return false;
          }
          if (this.value == '163183') {
              $('#ShippingOptions option[value="163183"]').prop('selected', true)
              return false;
          }
      });
  });
  </code></pre>
  
  <p>This works the first time I change the quantity. If I change the quantity a second time it doesn't work. How do I fix this so no matter how many times I change the quantity it works?</p>
  
  <p><strong>Update</strong></p>
  
  <p>The onchange event fires the first time but does not fire the second time. Why?</p>