JS比较两个日期格式的大小

if(document.all.TextBoxTimeStart.value!=""&&document.all.TextBoxTimeEnd.value!="")
{
                var checkStartDate = document.all.TextBoxTimeStart.value;  
                var checkEndDate = document.all.TextBoxTimeEnd.value;  
                //alert(checkStartDate+'--'+checkEndDate);
                var arys= new Array();  
                var startdate=new Date(arys[0],parseInt(arys[1]-1),arys[2]);   
                if(checkStartDate != null && checkEndDate != null)
                {  
                    arys=checkStartDate.split('-');  
                    var startdate=new Date(arys[0],parseInt(arys[1]-1),arys[2]);   
                    arys=checkEndDate.split('-');  
                    var checkEndDate=new Date(arys[0],parseInt(arys[1]-1),arys[2]);   
                    if(startdate > checkEndDate)
                    {  
                      alert("日期开始时间大于结束时间！");  
                      return false;  
                    }
                 }
}