function isAlphanumeric(elem, helpmsg)
{
	var alphaExp = /^[0-9a-zA-Z]+$/;
	
	if(elem.value.match(alphaExp))
		return true;
	else
	{
		alert(helpmsg);
		elem.focus();
		return false;
	}
}

function emailValidator(elem, helpmsg)
{
	var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	if(elem.match(emailExp))
		return true;
	else
	{
		alert(helpmsg);
		//elem.focus();
		return false;
	}
}

  /* affiche-masque la fin de l'article */

function affichage(object_id) {
  var obj=document.getElementById(object_id);
  if(obj.style.display == 'block')
    obj.style.display='none'
  else
    obj.style.display='block';
    if (object_id == 'fin-article')
      document.getElementById('lien-suite').style.display='none';
}