var code ; //在全局 定义验证码
     function createCode()
     { 
       code = "";
       var codeLength = 4;//验证码的长度
       var checkCode = document.getElementById("checkCode");
       var selectChar = new Array(0,1,2,3,4,5,6,7,8,9);//所有候选组成验证码的字符，当然也可以用中文的
        
       for(var i=0;i<codeLength;i++)
       {
      
        
       var charIndex = Math.floor(Math.random()*10);
       code +=selectChar[charIndex];
       
       
       }
//       alert(code);
       if(checkCode)
       {
         	document.getElementById("checkCode").innerHTML = code;
        
       }
       
     }
     
      function validate()
     {
      
       var txt = document.getElementById("validatetxt").value;
       if(txt.length <=0)
       {
           alert("请输入验证码！");
           return false;
       }
       else if(txt!= code )
       {
          alert("验证码输入错误！");
          createCode();//刷新验证码
          return false;
       }else{
         return true;
       }
    }
     


function messageTitleCheck(){
  var messageTitle=document.getElementById("messageBoardTitle").value;
  messageTitle=trim(messageTitle);
  if(messageTitle==""){
    alert("标题不能为空");
    document.getElementById("messageBoardTitle").focus();
    return false;
  }else{
   return true;
  }
  
}
function messageContentCheck(){
   var messageContent=document.getElementById("messageBoardContent").value;
     messageContent=trim(messageContent);
  if(messageContent==""){
    alert("内容不能为空");
     document.getElementById("messageBoardContent").focus();
    return false;
  }else{
   return true;
  }
}
function trim(ui)   
  {     
  var notValid=/(^\s)|(\s$)/;     
  while(notValid.test(ui)){     
    ui=ui.replace(notValid,"");   
    }     
  return ui;   
  }
function emailCheck() {
  
	var email = /^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/;
	var name = document.getElementById("messageBoarderEmail").value;
	if(name==""){
	 return true;
	}else{
	  if(email.test(name)){
	  return true;
	  }else{
	   alert("邮箱格式有误");
	    document.getElementById("messageBoarderEmail").focus();
	   return false;
	  }
	}
	
}