ElementTraversal.sample.js

/*
 * http://www.w3.org/TR/ElementTraversal/ にある
 * - firstElementChild
 * - nextElementSibling
 * - childElementCount
 * を使ったサンプル
 */
function traverseTree(element, indent) {
  var tagName = element.tagName;
  var child = element.firstElementChild;
  var childCount = element.childElementCount;
  
  console.log(indent + tagName);

  while (child) {
    traverseTree(child, indent + "  ");
    child = child.nextElementSibling;
  }
}

var time = 0;
time = new Date();
traverseTree(document.body, "");
time = new Date() - time;
console.log("total time: " + time);