YAHOO.util.Event.onDOMReady(function () {
   
   // as soon as the DOM is complete, look for the contact form
   var contact_form = YAHOO.util.Dom.get("contact_form");
   
   // if it's here, register a validation function
   if (contact_form !== null) contact_form.onsubmit = function () {
      
      // full name
      var full_name = YAHOO.util.Dom.get("full_name");
      if (full_name !== null) {
         // one or more non-whitespace characters
         if (!/[^\s]+/.test(full_name.value)) {
            alert("Please enter your full name.");
            full_name.select();
            full_name.focus();
            return false;
         }
      } else return false; // huh??
      
      // email address
      var email_address = YAHOO.util.Dom.get("email_address");
      if (email_address !== null) {
         if (!/^\s*([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+\s*$/.test(email_address.value)) {
            alert("Please enter a valid email address.");
            email_address.select();
            email_address.focus();
            return false;
         }
      } else return false;
      
      // message
      var message = YAHOO.util.Dom.get("message");
      if (message !== null) {
         // one or more non-whitespace characters
         if (!/[^\s]+/.test(message.value)) {
            alert("You cannot send a blank message! Please enter something.");
            message.select();
            message.focus();
            return false;
         }
      } else return false;
      
      // captcha
      var message = YAHOO.util.Dom.get("security_code");
      if (message !== null) {
         // one or more non-whitespace characters
         if (!/[^\s]+/.test(message.value)) {
            alert("Please enter the security code provided.");
            message.select();
            message.focus();
            return false;
         }
      } else return false;
      
      return true;
   }
});