My Solution to Tree Walker (nextNode)

[Robert Nantchouang Nantchouang]

// Returns next node of DOM tree or null if no next node is found.

nextNode = function(node) {

  // Handles case for null input.

  if (node == null) {

    return null;

  }

  

  if (node.firstChild != null) {

    return node.firstChild;

  }

  if (node.nextSibling != null) {

    return node.nextSibling;

  }

  

  // If loop iterates back to the root, the DOM tree has no next node so it stops.

  while (node != null && node.nextSibling == null) {

    node = node.parentNode;

  }

  

  return node == null ? null : node.nextSibling;

};