in use here.js

    set dirty(value) { 
      this.ascend(function(node) { node._dirty = value; });
    },

used like.js

node.dirty = true; // marks current node and all parents dirty

walk.js

    walk : function(map, callback, depth) {
      var levels   = (depth) ? depth-1 : null,
          fnResult = false, // false means stop!
          walker   = {
            _stopped : false,
            stop     : function() {
              walker._stopped = true;
            },
            stopped  : function() {
              return walker._stopped;
            },
            nodesWalked : 1,
          };

      if (typeof callback === "function") {
        fnResult = callback(this, walker);
      }

      if (fnResult !== false && 
          (levels === null || levels >= 0) &&
          walker.stopped() === false)
      {
        map(this, function(currentNode) {
          currentNode.walk(map, callback, levels);
        });
      }
      return walker;
    },

    ascend  : function(fn, depth) {
      this.walk(function(node) {
        if (node && node.parent) {
          fn(node.parent);
        }
      },fn, depth);
    },

    descend : function(fn, depth) {
      this.walk(
      function(node) {
        var l=node.children.length, i=0, result;
        for (i; i<l; i++)
        {
          fn(node.child(i));
        }
      }, fn, depth);
    },