function isEmpty(s)
{  
	return ((s == null) || (s.length == 0))
}

function isWhitespace (s)
{  
  var whitespace = " \t\n\r";
  var i;

   for (i = 0; i < s.length; i++)
   {   
       var c = s.charAt(i);
       if (whitespace.indexOf(c) >= 0) 
	   {
		  return true;
	   }
   }
   return false;
}

function isCharsInBag (s, str)
{  
  var i;
  for (i = 0; i < s.length; i++)
  {   
      var c = s.charAt(i);
      if (str.indexOf(c) == -1) return false;
  }
  return true;
}

function isEmail (s)
{
    if (isEmpty(s))
	{
		window.alert("E-mail地址不能为空，请输入！");	
		return false;
	}
    if (isWhitespace(s))
	{
		window.alert("E-mail地址中不能包含空格符，请重新输入！");	
		return false;
	}
   var i = 1;
   var len = s.length;
	pos1 = s.indexOf("@");
	pos2 = s.indexOf(".");
	pos3 = s.lastIndexOf("@");
	pos4 = s.lastIndexOf(".");

	if ((pos1 <= 0)||(pos1 == len)||(pos2 <= 0)||(pos2 == len))  
	{
		window.alert("请输入有效的E-mail地址！");
		return false;
	}
	else
	{

		if( (pos1 == pos2 - 1) || (pos1 == pos2 + 1) 
		  || ( pos1 != pos3 )  //find two @
		  || ( pos4 < pos3 ) ) //. should behind the '@'  		
		{
			window.alert("请输入有效的E-mail地址！");
			return false;
		}
	}

	if ( !isCharsInBag( s, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-_@"))
	{
		window.alert("E-mail地址中包含非法字符");
		return false;
	}
	return true;
}
function parseNum(theNum){
  if (theNum.substring(0,1)==0)
    theNum=theNum.substring(1)
  return theNum
}
function parseYMD(theYear,theMonth,theDay) {
  theYear=parseNum(theYear)
  theMonth=parseNum(theMonth)
  theDay=parseNum(theDay)
  if ((theYear < 1900) || (theYear > 2100)){
    return 1
  }
  if (theMonth < 1 || theMonth > 12){
    return 2
  }
  if ((theMonth==1 || theMonth==3 || theMonth==5 || theMonth==7 || theMonth==8 || theMonth==10 || theMonth==12) &&
      (theDay <1 || theDay > 31)
     ){
    return 3
  }
  if ((theMonth==4 || theMonth==6 || theMonth==9 || theMonth==11) &&
      (theDay <1 || theDay > 30)
     ){
    return 3
  }
  if (theYear%400==0 || (theYear%4==0 && theYear%100!=0)){  //闰年
    if (theMonth==2 && (theDay <1 || theDay > 29) )
      return 3
  }
  else  //平年
    if (theMonth==2 && (theDay <1 || theDay > 28) )
      return 3
  return 0
}

function isInvalidDate(theDate,separator){
  default_style=2
  if (theDate.length>10 || theDate.length<8)
    return true
  idx1=theDate.indexOf(separator)
  if (idx1==-1)
    return true
  idx2=theDate.indexOf(separator,idx1+1)
  if (idx2==-1)
    return true
  if (isInvalidDate.arguments.length>2)
  	default_style=isInvalidDate.arguments[2]
  if (default_style<1 || default_style>9){
  	alert("传入参数有误！请检查。")
	return true
  }
  if (default_style==1){
  theYear=theDate.substring(0,idx1)
  theMonth=theDate.substring(idx1+1,idx2)
  theDay=theDate.substring(idx2+1)
  }
  if (default_style==2){
  theMonth=theDate.substring(0,idx1)
  theDay=theDate.substring(idx1+1,idx2)
  theYear=theDate.substring(idx2+1)
  }
  if (theDay.length>2)
    return true
  if (parseYMD(theYear,theMonth,theDay)>0)
    return true
  else
    return false
}