下面这段javascript在IE下能work, FF下不行，怎么修改

<script language="javascript">
    function getPrice(id)
    {
        var item_danjia = document.all.item("danjia"+id);      
        var item_shuliang = document.all.item("shuliang"+id);
        var item_zongjia = document.all.item("zongjia"+id);
        var danjia = parseInt(item_danjia.innerHTML);
        if(isNaN(item_shuliang.value)){
            alert("Please input digital!");
            shuliang.value = "";
            item_zongjia.innerHTML = "";
        }            
        if(item_shuliang.value==""){
            item_zongjia.value = "";
        }else{
            var sl = parseInt(item_shuliang.value);
            var zj = parseFloat(danjia*sl);
            item_zongjia.innerHTML = String(zj);
        }            
    }
</script>
<table  cellspacing="0" cellpadding="0" border="0" width = "600">
<tr >
    <th ><b>Products</b></th>
    <th style="text-align:center;"><b>Qty</b></th>
    <th>Price</th>
    <th>Copy</th>
    <th>Cost</th>
    <th>Order</th>
</tr>
<tr>
    <th><img src = "../image/into.gif">BMS-536924</th>
    <th style="text-align:center;">50MG</th>
    <th><label id = "danjia0">890</label>$</th>
    <th><input type = "text" name = "shuliang0" value = "1" size = "1" onKeyUp="getPrice(0)"></th>
    <th><label id = "zongjia0">890</label>$</th>
    <th><input type = "checkbox" name= "ORDERID[]" value = "0" checked></th>
</tr>
<tr>
    <th><img src = "../image/into.gif">BMS-536924</th>
    <th style="text-align:center;">50MG</th>
    <th><label id = "danjia1">890</label>$</th>
    <th><input type = "text" name = "shuliang1" value = "1" size = "1" onKeyUp="getPrice(1)"></th>
    <th><label id = "zongjia1">890</label>$</th>
    <th><input type = "checkbox" name= "ORDERID[]" value = "1" checked></th>
</tr>
</table>