serialize

 Mif.Tree = new Class({
     serialize: function(items){
         var serial = [];
         if (!items) items = this.root.getChildren();
         items.each(function(el, i){            
         serial[i] = {
                 id: el.id,
                 children: (el.getChildren()) ? tree.serialize(el.getChildren()) : []
             };
         });
         return serial;
     }
 });

     var request = function() {
        
         var theDump = tree.serialize();
         var req = new Request({
                 method: 'post',            
                 url: "save-list.php", onSuccess:
                     function(html) {
                         $('debug').empty().set('text',html);
                     }
         }).send('m='+JSON.encode(theDump));
     };