function isLeapYear(year){
 if(year % 4 == 0 && ((year % 100 != 0) || (year % 400 == 0))){
     return true;
 }
 return false; 
}

function validatePeriod(fyear,fmonth,fday,byear,bmonth,bday){
 if(fyear < byear){
  return true;
 }else if(fyear == byear){
  if(fmonth < bmonth){
   return true;
  } else if (fmonth == bmonth){
   if(fday <= bday){
    return true;
   }else {
    return false;
   }
  } else {
   return false;
  }
 }else {
  return false;
 }
}
//计算两个日期的差值
function compareDate(date1,date2){
    var regexp=/^(\d{1,4})[-|\.]{1}(\d{1,2})[-|\.]{1}(\d{1,2})$/;
    var monthDays=[0,3,0,1,0,1,0,0,1,0,0,1];
    regexp.test(date1);
    var date1Year=RegExp.$1;
    var date1Month=RegExp.$2;
    var date1Day=RegExp.$3;

    regexp.test(date2);
    var date2Year=RegExp.$1;
    var date2Month=RegExp.$2;
    var date2Day=RegExp.$3;

 if(validatePeriod(date1Year,date1Month,date1Day,date2Year,date2Month,date2Day)){
  firstDate=new Date(date1Year,date1Month,date1Day);
     secondDate=new Date(date2Year,date2Month,date2Day);
  
     result=Math.floor((secondDate.getTime()-firstDate.getTime())/(1000*3600*24));
     for(j=date1Year;j<=date2Year;j++){
         if(isLeapYear(j)){
             monthDays[1]=2;
         }else{
             monthDays[1]=3;   
         }
         for(i=date1Month-1;i<date2Month;i++){
             result=result-monthDays[i];
         }
     }
     return result;
 }else{
  return 'the first field must before the second date.';
 }
}