js计算表格的值(例如购物车中)

 <script language="JavaScript" type="text/javascript" src="../js/jquery-1.7.min.js"></script> <script language="javascript" type="text/javascript">  function   trim(str){return   str.replace(/^\s+|\s+$/,'')} function checkisempty(obj) {    var number=obj.value;  var tr = obj.parentNode.parentNode;  var tdpricevalue=$("#tbShopCar tr:eq(1) td:nth-child(7)").html();  var tdnumbervalue=$('#tbShopCar td').find('input').val()   //$("#table1 tr:eq(1) td:nth-child(1)").html("value");//设置table1,第2个tr的第一个td的值  var qua=tdpricevalue*tdnumbervalue; $("#tbShopCar tr:eq(1) td:nth-child(8)").html(qua.toFixed(2));//相乘后结果保留两位小数} </script>