function isblank(s)
  {
  for (var i=0; i<s.length; i++)
    {
    var c=s.charAt(i);
    if (c != ' ' && c != '\n' && c != '\t') return false;
    }
  return true;
  }

/* Author: reynardmh
   Date: 1-Dec-2000
   Desc: Basic check for valid email address
     Only check if contains '@' 
          has string before '@' 
          has '.' after '@'
*/
function valid_email(email)
  {
  var middle = email.indexOf('@',1);
  if (middle > 0)
    {
    if (email.indexOf('.', middle+2) > 0)
      return true;
    }
  return false;
  }

/* Author: reynardmh
   Date: 1-Dec-2000 
   Desc: return true if all elements that is required (optional is not set to true) is not blank
   
   Notes: 
   * If the element is in email format, the email property of the element must be set to true so 
     it will check for valid email format eg: this.email_address.email = true;
   * In order that the error message displays the human readable format for
     the fields name, give name for each elements in the desc property.
     eg: this.fname.desc = "First Name";
*/
function validate(f)
  {
  var msg;
  var empty_fields = "";
  var error = "";
  
  for (var i=0; i < f.length; i++)
    {
    var e = f.elements[i];
    if (e.email)
      {
      if (e.optional)
        {
        if (e.value != null && e.value != "" && !isblank(e.value))
          {
          if (!valid_email(e.value)) 
            error += "Email address is not valid\n";
          }
        }
      else 
        {
        if (!valid_email(e.value)) 
          error += "Email address is not valid\n";
        }
      }
    else if ((e.type == "text" || e.type == "textarea" || e.type == "password") && !e.optional)
      {
      if (e.value == null || e.value == "" || isblank(e.value))
        {
        if (e.desc != null) 
          empty_fields += "\n     " + e.desc;
        else 
          empty_fields += "\n     " + e.name;
        }
      }
    else if (e.type == "select-one" && !e.optional)
      {
      if (e.options[e.selectedIndex].value == null || e.options[e.selectedIndex].value == "" 
          || isblank(e.options[e.selectedIndex].value))
        {
        error += "Select appropriate value for ";
        if (e.desc != null) 
          error += e.desc + "\n";
        else 
          error += e.name + "\n";
        }
      }
    }
  if (!empty_fields && !error)
    return true;
  
  msg = "";
  if (empty_fields)
    msg += "The following required field(s) are empty:" + empty_fields + "\n\n";
  msg += error;  
  alert (msg);
  return false;
  }