请教jquery的blur的问题和单独js中判断数字的问题！

Question

1.页面代码：
<tr>
<th>序号</th>
<th>名称</th>
<th>单价</th>
<th>重量</th>
<th>价格</th>
</tr><tr class="product">
<th>1</th>
<td></td>
<td></td>
<td></td>
<td></td> 
</tr> 实现了可以实时编辑表单数据，就是在td中加入input标签，
在单独js中通过$(".product td:nth-child(3) input").val()可以获取该数据，我想通过blur来alert失去焦点后写入的数据，请问怎么写代码？ 2.在单独js中通过var price = $(".product td:nth-child(3) input").val()可以获取数据，然后写上if(isNaN(price)){alert("单价必须为数字")；}就出错了，FF没有报错，原来的样式没有，原来的可以实时编辑的表格也不能编辑，只是在点了页面上的按钮后报错！

Answer 1

<script src="js/jquery-1.3.2.js" type="text/javascript"> </script> 
<script type="text/javascript"> 
window.onload=function(){
$("tbody td").click(function(){
            var obj = $(this);
            if(obj.children("input").length > 0){
                return false;
            }
            var text = obj.html();
            obj.html("");
            var inputObj = $("<input type='text'>").css("border-width","0").css("font-size","16px")
                .width(obj.width()).css("background-color",obj.css("background-color")).css("text-align","center")
                .val(text).appendTo(obj).blur(function(){
                 var s = $(this).val();
                 if(isNaN(s)) {alert("不是数字");$(this).focus()}
                 else alert(s);
            });
            inputObj.trigger("focus").trigger("select");
            inputObj.click(function(){
                return false;    
            }) ;
});}
function doit(){
  $(".product td:nth-child(5) input").each(function(){
     alert($(this).val())    
  })
}
</script>
<input type="button" onclick="doit();" value="click">
<table>
<tbody id="tbody"> 
            <tr> 
                <th>序号 </th> 
                <th>名称 </th> 
                <th>单价 </th> 
                <th>重量 </th> 
                <th>价格 </th> 
            </tr>
            <tr class="product"> 
                <td>1</td> 
                <td>xxx</td> 
                <td>1.2</td> 
                <td>1.3</td> 
                <td>1.4</td>    
            </tr> 
            <tr class="product"> 
                <td>2</td> 
                <td>xxx</td> 
                <td>2.2</td> 
                <td>2.3</td> 
                <td>2.4</td>    
            </tr> 
</tbody> 
</table>

Answer 2

<script src="js/jquery-1.3.2.js" type="text/javascript"> </script> 
<script type="text/javascript"> 
window.onload=function(){
$("tbody td:nth-child(3), tbody td:nth-child(4)").click(function(){
            var obj = $(this);
            if(obj.children("input").length > 0){
                return false;
            }
            var text = obj.html();
            obj.html("");
            var inputObj = $("<input type='text'>").css("border-width","0").css("font-size","16px")
                .width(obj.width()).css("background-color",obj.css("background-color")).css("text-align","center")
                .val(text).appendTo(obj).blur(function(){
                    var s = $(this).val();
                    if(isNaN(s)) {alert("不是数字");$(this).focus()}
                    else{
                     var obj1 = $(this).parent().parent().children("td:nth-child(3)");
                     var obj2 = $(this).parent().parent().children("td:nth-child(4)");
                     if(obj1.children().filter("input").length==0) k1= obj1.text();
                     else k1 = obj1.children().filter("input").val();
                     if(obj2.children().filter("input").length==0) k2= obj2.text();
                     else k2 = obj2.children().filter("input").val();
                     var sum = Math.round(k1*k2*100)/100;
                     $(this).parent().parent().children("td:nth-child(5)").html(sum);
                    };
            });
            inputObj.trigger("focus").trigger("select");
            inputObj.click(function(){
                return false;    
            }) ;
});}
function doit(){
  $(".product td:nth-child(5) input").each(function(){
     alert($(this).val())    
  })
}
</script>
<input type="button" onclick="doit();" value="click">
<table>
<tbody id="tbody"> 
            <tr> 
                <th>序号 </th> 
                <th>名称 </th> 
                <th>单价 </th> 
                <th>重量 </th> 
                <th>价格 </th> 
            </tr>
            <tr class="product"> 
                <td>1</td> 
                <td>xxx</td> 
                <td>1.2</td> 
                <td>1.3</td> 
                <td>1.4</td>    
            </tr> 
            <tr class="product"> 
                <td>2</td> 
                <td>xxx</td> 
                <td>2.2</td> 
                <td>2.3</td> 
                <td>2.4</td>    
            </tr> 
</tbody> 
</table>