javascript多消息表单验证

Question

I m using a jquery system in order to validate input in an html form. In the email field I want to display either validate[required] or custom[email] that represent 2 error messages (but not both). Im not too skilled in Javascript but here's my attempt

<form id="formID1" action="report-problem.asp" name="varsForm1" method="post">
<script language="Javascript">...

        function IsEmpty(){
          var class = "";
          if(document.forms['formID1'].email1.value == "")
          {
            class='validate[required]'; 
          }
          else 
          {
               class= 'validate[custom[email]]'; 
          }
          return class;
        }
     </script>

    <td>Email Address</td>
    <td class="input" width="302"><input name="email1" type="text" id="email1" class="IsEmpty();" value="" /></td>....
<input name="" id="submitbtn" type="submit" value="Send" />

Answer 1

if(document.forms['formID1'].email1.value == "")
  {
   $("#email1").removeClass('validate[custom[email]]');
    class='validate[required]'; 
  }
  else 
  {
       $("#email1").removeClass('validate[required]'); 
       class= 'validate[custom[email]]'; 
  }
  return class;  

You should remove previous class when you adding new error class in your email field. It should Work :)