function display(y){$(y).style.display=($(y).style.display=="none")?"":"none";} 
function $(s){return document.getElementById(s);}

function testMesLen(mes){
document.all.mesLen.value=500-mes.value.length;
if (document.all.mesLen.value<0){
 alert("您输入的留言过长，请控制在500字以内!");
 mes.value=mes.value.substring(0,500);
}
}

function lTrim(str) 
{ 
if (str.charAt(0) == " ") 
{ 
//如果字串左边第一个字符为空格 

str = str.slice(1);//将空格从字串中去掉 
//这一句也可改成 str = str.substring(1, str.length); 
str = lTrim(str); //递归调用 
} 
return str; 
} 

//去掉字串右边的空格 
function rTrim(str) 
{ 
var iLength; 

iLength = str.length; 
if (str.charAt(iLength - 1) == " ") 
{ 
//如果字串右边第一个字符为空格 
str = str.slice(0, iLength - 1);//将空格从字串中去掉 
//这一句也可改成 str = str.substring(0, iLength - 1); 
str = rTrim(str); //递归调用 
} 
return str; 
} 

//去掉字串两边的空格 
function trim(str) 
{ 
return lTrim(rTrim(str)); 
}
function Checklogin(){	
if(trim(document.liuyan.username.value)=='')
{alert("系统提醒：请填写您的姓名！");document.liuyan.username.focus();return false;}
if(document.liuyan.email.value.length!=0)
  {if (document.liuyan.email.value.charAt(0)=="." ||        
         document.liuyan.email.value.charAt(0)=="@"||       
         document.liuyan.email.value.indexOf('@', 0) == -1 || 
         document.liuyan.email.value.indexOf('.', 0) == -1 || 
         document.liuyan.email.value.lastIndexOf("@")==document.liuyan.email.value.length-1 || 
         document.liuyan.email.value.lastIndexOf(".")==document.liuyan.email.value.length-1)
     {alert("Email地址格式不正确！");
      document.liuyan.email.focus();
      return false;}}
if(trim(document.liuyan.tel.value)=='')
{alert("系统提醒：请填写您的联系方式！");document.liuyan.tel.focus();return false;}
if(trim(document.liuyan.content.value)=='')
{alert("系统提醒：请填写留言内容！");document.liuyan.content.focus();return false;}
}