function compareDate(DateOne, DateTwo) {
  var OneMonth = DateOne.substring(5, DateOne.lastIndexOf("-"));
  var OneDay = DateOne.substring(DateOne.length, DateOne.lastIndexOf("-") + 1);
  var OneYear = DateOne.substring(0, DateOne.indexOf("-"));
  var TwoMonth = DateTwo.substring(5, DateTwo.lastIndexOf("-"));
  var TwoDay = DateTwo.substring(DateTwo.length, DateTwo.lastIndexOf("-") + 1);
  var TwoYear = DateTwo.substring(0, DateTwo.indexOf("-"));
  if (Date.parse(OneMonth + "/" + OneDay + "/" + OneYear) > Date.parse(TwoMonth + "/" + TwoDay + "/" + TwoYear)) {
    return true;
  } else {
    return false;
  }
}

var checkStartDate = document.form1.checkStartDate.value; 
var checkEndDate = document.form1.checkEndDate.value; 
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("你的检查日期开始时间大于结束时间啦"); 
    return; 
  }
}