关于验证输入内容的问题

写出来了,呵呵
<html>
<head>
      <script language="javascript"> 
         function checkData() 
         { 
            if(document.all.txtAccount.value=="1") 
            { 
               alert("正确"); 
               return true; 
            } 
    if(document.all.txtAccount.value=="5")
    { 
               alert("正确"); 
               return true; 
            } 
            
  if(document.all.txtAccount.value=="") 
            { 
               alert("您的输入不能为空");
return false; 
            } 
 
else
        {
        alert("您的输入不正确");
        }       }       </script> 
</head><body>
<input type="text" name="txtAccount" size=15><br><br>
<input type="button" value="验证" onClick="checkData()">
</body></html>