code: function walk(node, callback)
  {
  	var childNode,i;
  	
  	if (callback(node) === false) return false;
  	
  	if (node.childNodes != null)
  	{
  		i = 0;
  		childNode = node.childNodes[i];
  	}
  	
  	while (childNode != null)
  	{
  		if (walk(childNode, callback) === false) return false;
  		
  		childNode = node.childNodes[++i];
  	}
  }
docs: TODO :: contribute these to npmjs.com/dom-walk