var errormsg="";
function clearError()//goi ham` nay truoc
{
   errormsg="";
}
function checkEmail(email)
{
   var at1      =  email.indexOf("@");
   var at2      =  email.lastIndexOf("@");
   var dot     =  email.indexOf(".");
   var space   =  email.indexOf(" ");
   if((at1!=-1)&&
      (at1!=0)&&
      (at2==at1)&&
      (dot!=-1)&&
      (dot>at1+1)&&
      (dot<email.length-1)&&
      (space==-1))
   {
      return true;
   }
   else
   {
      errormsg=errormsg+"- Email address is illegal.\n";
      return false;
   }
}
function checkDate(dd,mm,yyyy,name)
{
   result=true;
   if(!isNaN(yyyy)&&(yyyy!="")&&(yyyy<10000))	
   {
      if( (mm=="02") && ((dd=="30")||(dd=="31")) )
         result=false;
      if( (mm=="02") && (dd=="29") && (yyyy%4>0) )
         result=false;
      if( ((mm=="04")||(mm=="06")||(mm=="09")||(mm=="11")) && (dd=="31") )
         result=false;
   }
   else
   {
      result=false;
   }
   if(result==false)
      errormsg=errormsg+"- "+name+" is illegal .\n"	
   return result;
}
function checkInterval(dstart,mstart,ystart,names,dend,mend,yend,namee)
{
   var re=true;
   re=checkDate(dstart,mstart,ystart,names)&&checkDate(dend,mend,yend,namee);   
   if(re)
   {
      var yyyy=yend-ystart;
      if(yyyy>0)
	 re=true;
      else if(yyyy==0)
      {
         var mm=mend-mstart;
         if(mm>0)
            re=true;
         else if(mm==0)
         {
            var dd=dend-dstart;
	    if(dd>0)
	       re=true;
            else
               re=false; 		 
         }
         else
	    re=false; 
      }
      else
         re=false; 	
   }
   if(re==false)
      errormsg=errormsg+"- Interval time is illegal .\n";
   
   return re; 
}
function checkTextField(str,name)
{
	if(str=="")
		errormsg=errormsg+"- "+name+" must not null .\n";
}
function checkRadio(val,name)
{
	var legal=false;
	for(var i=0;i<val.length;i++)
	{
		if(val[i].checked==true)
		{
			legal=true;
		}
	}
	if(legal==false)
		errormsg=errormsg+"- "+name+" must select one.\n";
}
function checkChoice(val,name)
{
	if(val<0)
		errormsg=errormsg+"- "+name+" must select one .\n"; 
}
function checkIsNum(val,name)
{
	if((val!="")&&(!isNaN(val)))
		return true;
	else
	{	
		errormsg=errormsg+"- "+name+" is not a number . \n";
	}

}

function overMe(th)
{
	th.style.background='#FFFFFF';
}

function outMe(th)
{
	th.style.background='#EEF5FB';
}
function checkAll()
{
	if(errormsg!="")
	{
		alert("PLEASE CHECK FORM AGAIN !      \n\n"+errormsg);
		return false;
	}
	else
		return true;
}