function checkForm(message1, message2){
  require = '';
  agree = '';
  if (document.getElementById('name').value == ''){
    require += ' Nom';
  }
  if (document.getElementById('email').value == ''){
    require += ' E-mail';
  }
  if (document.getElementById('userCountry').value == ''){
    require += ' Pays';
  }
  if (document.getElementById('city').value == ''){
    require += ' Ville';
  }
  if (document.getElementById('agree').checked == false){
    agree += message2;
  }
  if (require == '' && agree == ''){
    return true;
  }
  else{
    message = '';
    message = ((require != '') ? message1 + ": " + require + '<br />' : '') +
              ((agree != '') ?  agree + '<br />' : '') + '<br />';
    document.getElementById('errorInfo').innerHTML = message;
    return false;
  }
}