Função para ocultar ou exibir elemento

/*******************************************************************
Função para exibir o elemento
*******************************************************************/
function f_exibe(elem) {
var el = document.getElementById(elem);

if(el.style.display == 'none'){
el.style.display = 'block';
}else{
el.style.display = 'block';
}
}

/*******************************************************************
Função para ocultar o elemento
*******************************************************************/
function f_esconde(id) {
var e = document.getElementById(id);
if(e.style.display == 'block')
e.style.display = 'none';
else
e.style.display = 'none';
}