View difference between Paste ID: 00zGhKU5 and mUVsuJ8m

 var generatedContent = {};
 
 function checkbox_onchange(checkbox) {
   var name = checkbox.value;
   var node = generatedContent[name];
 
   if (checkbox.checked) {
     if (undefined == node || null == node) {
       // on crée juste un <div>NOEUD {name}</div>
       node = document.createElement('div');
       node.appendChild(document.createTextNode('NOEUD '+ name));
 
       // on ajoute ça dans l'arbre DOM.
       document.getElementById('contenu').appendChild(node);
 
       generatedContent[name] = node;
     }
     node.style.display = 'block'; // affiche le noeud.
 
   } else if (!(undefined == node || null == node)) {
     node.style.display = 'node'; // cache le noeud.
   }
 }
 
 var etatInitial = {b1: true, b2: false};
 function bidule() {
   for (var i in etatInitial) {
     var b = etatInitial[i];
     document.getElementById(i).checked = b;
     checkbox_onchange(b);
   }
 }