function MM_findObj(n, d) { //v4.0 
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) { 
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);} 
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n]; 
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document); 
if(!x && d.getElementById) x=d.getElementById(n); return x; 
} 
function MM_showHideLayers() 
{ //v3.0 
var i,p,v,obj,args=MM_showHideLayers.arguments; 
for (i=0; i<(args.length-2); i+=3) 
if ((obj=MM_findObj(args[i]))!=null) 
{ 
v=args[i+2]; 
if (obj.style) 
{ 
obj=obj.style; 
v=(v=='show')?'visible':(v=='hide')?'hidden':v; 
} 
obj.visibility=v; 
} 
} 

function isWhitespace (s)
{  
  var whitespace = "";
  var i;
   for (i = 0; i < s.length; i++)
   {   
       var c = s.charAt(i);
       if (whitespace.indexOf(c) >= 0) 
	   {
		  return true;
	   }
   }
   return false;
}
function isEmail (s)
{
    if (isWhitespace(s))
	{
		alert("输入的电子邮箱地址中不能包含空格符，请重新输入！");	
		return false;
	}

   var i = 1;
   var len = s.length;
   var vmail = 0;
	if (len > 50)
	{
		alert("电子邮箱地址长度不能超过50位!");
		return false;
	}
	pos1 = s.indexOf("@");
	pos2 = s.indexOf(".");
	pos3 = s.lastIndexOf("@");
	pos4 = s.lastIndexOf(".");
	if ((pos1 <= 0)||(pos1 == len)||(pos2 <= 0)||(pos2 == len))  
	{
		alert("您填入的电子邮箱格式不正确，请检查有无拼写错误！");
		return false;
	}
	else
	{
		if( (pos1 == pos2 - 1) || (pos1 == pos2 + 1) 
		  || ( pos1 != pos3 )  //find two @
		  || ( pos4 < pos3 ) ) //. should behind the '@'  		
		{
			alert("您填入的电子邮箱格式不正确，请检查有无拼写错误！");
			return false;
		}
	}
	return true;
}