addLoadListener(init);

function init()
{
  document.forms[0].onsubmit = validateFields;
  return true;
}

function validateFields() {
  var elements = document.forms[0].elements;
   var menserror = 'El formulario no puede ser enviado.\n';
    var botxt =  document.getElementById('env_bot').value;
document.getElementById('env_bot').value = "Espere, por favor...";
document.getElementById('env_bot').disabled = true;
var emailPattern = /^[\w\.\-]+@([\w\-]+\.)+[a-zA-Z]+$/;

  
    for (var i = 0; i < elements.length; i++)  {
		elements[i].style.backgroundColor = "#ffffff";
  
if (/(^| )valEmail( |$)/.test(elements[i].className) && !emailPattern.test(elements[i].value))
    {
		elements[i].focus();
		elements[i].style.backgroundColor = "#f0f0f0";
		quien = elements[i].name;
		mailmal = menserror;
		mailmal = mailmal + '\nEl email no parece válido.';
		alert(mailmal);
		document.getElementById('env_bot').value = botxt;
		document.getElementById('env_bot').disabled = false;
		return false;
    }
	
	if (/(^| )valUsuario( |$)/.test(elements[i].className) && elements[i].value == "")
    {
		elements[i].focus();
		elements[i].style.backgroundColor = "#f0f0f0";
		quien = elements[i].name;
		mailmal = menserror;
		mailmal = mailmal + '\nPor favor rellene la casilla del nombre de usuario.';
		alert(mailmal);
		document.getElementById('env_bot').value = botxt;
		document.getElementById('env_bot').disabled = false;
		return false;
    }
	



	}
	
return true;

}

function addLoadListener(fn)
{
  if (typeof window.addEventListener != 'undefined')
  {
    window.addEventListener('load', fn, false);
  }
  else if (typeof document.addEventListener != 'undefined')
  {
    document.addEventListener('load', fn, false);
  }
  else if (typeof window.attachEvent != 'undefined')
  {
    window.attachEvent('onload', fn);
  }
  else
  {
    var oldfn = window.onload;
    if (typeof window.onload != 'function')
    {
      window.onload = fn;
    }
    else
    {
      window.onload = function()

      {
        oldfn();
        fn();
      };
    }
  }
}