关于无法同时在IE和Firefox中，正常将日期数增加的问题

Question

function adddays(){
        var strFromDate = document.getElementById("StartDate").value;var dObj;
if(document.all)
        dObj = new Date(strFromDate.replace("-",","));   // 注意，这里！
else
        dObj = new Date(strFromDate.replace(/-/g,","));
            var millisecond=1;
        var second=millisecond*1000;
        var minute=second*60;
        var hour=minute*60;
        var day=hour*24;
        var year=day*365;        var dVal = new Date(dObj);
        var dVal=dVal.valueOf();
        var newDate;
        newDate=new Date(dVal+day*3);        newDate = new Date(newDate)
       
        document.getElementById("nextDay").innerHTML=newDate.getFullYear() + "-" + (newDate.getMonth() + 1) + "-" + newDate.getDate();    }