var fieldstocheck = new Array();
fieldnames = new Array();

function checkform() {
  for (i=0;i<fieldstocheck.length;i++) {
    if (eval("document.subscribeform.elements['"+fieldstocheck[i]+"'].value") == "") {
      alert("Favor preencher o campo "+fieldnames[i]);
      eval("document.subscribeform.elements['"+fieldstocheck[i]+"'].focus()");
      return false;
    }
  }
  document.subscribeform.submit();
  return true;
}

function addFieldToCheck(value,name) {
  fieldstocheck[fieldstocheck.length] = value;
  fieldnames[fieldnames.length] = name;
}

function compareEmail()
{
  return (document.subscribeform.elements["email"].value == document.subscribeform.elements["emailconfirm"].value);
}

addFieldToCheck("nome","Nome");
addFieldToCheck("email","E-mail");
addFieldToCheck("fone","Fone"); 
addFieldToCheck("mensagem","Mensagem");