Cambiar visibility o display en un botón

[_cronos2]

Código Javascript:

function cambia(a, b){
 var id1 = document.getElementById(a);
 var id2 = document.getElementById(b);
 if(id1.style.display=='block'){
  id1.style.display = 'none';
  id2.style.display = 'block';
 }else{
  id1.style.display = 'block';
  id2.style.display = 'none';  
 }
}
//o más simple
function cambia(a, b){
 var id1 = document.getElementById(a);
 var id2 = document.getElementById(b);
 id1.style.display = (id1.style.display == 'block') ? 'none' : 'block';
 id2.style.display = (id1.style.display == 'block') ? 'none' : 'block';
}
 

Código HTML:

<input type='button' value='Ver / No ver' onclick='cambia("id1", "id2");' />
<div id='id1' style='display:block;'>1</div>
<div id='id2' style='display:none;'>2</div>
 

Saludos (: