Js中比较时间大小

function compareTime()

{
        var sDate=form1.kssj.value;
        var eDate=form1.jssj.value;
        var startDate = new Date(sDate.replace("-",",")).getTime() ;
        var endDate = new Date(eDate.replace("-",",")).getTime() ;
       if( startDate > endDate )
        {
              alert("开始时间不能大于结束时间！");
              return false;
        }
         return true;