js控制input框输入数字时，累计求和

input框输入数字时,自动开始计算累加

<div class="form-group">
   <label for="inputPassword3" class="col-sm-2 control-label"><?php echo $this->translate('申请类型');?></label>
   <div class="col-sm-5">
      <div>
      <input type="checkbox" id="logistics_type1" name="logistics_type[]" value="1" />产品码

         申请数量<input  type="text" class="form-control number" name="product_section_number" id="product_section_number"  value="">

      </div>
      <div>
      <input type="checkbox" name="logistics_type[]" id="logistics_type2" value="2" />箱码

         申请数量<input type="text" class="form-control number" name="box_section_number" id="box_section_number"  value="">

      </div>
      <div>
      <input type="checkbox" name="logistics_type[]" id="logistics_type3" value="3" />小箱码

         申请数量<input type="text" class="form-control number" name="small_box_section_number"  id="small_box_section_number"  value="">

      </div>
      <div>
      <input type="checkbox" name="logistics_type[]" id="logistics_type4" value="4" />堆垛码

         申请数量<input type="text" class="form-control number" name="stack_section_number"  id="stack_section_number"  value="">

      </div>

   </div>
</div>

<script type="text/javascript">
   $('.number').bind('input propertychange', function(){
      var total = 0;
      $(".number").each(function(){
         total+=(parseFloat($(this).val())?parseFloat($(this).val()):0);
      });
      $("#quantity").val(total);
   });

</script>