function getDef(element, def) {
  var str = ""

  var childs = element.childNodes
  for (var i = 0; i < childs.length; ++i) {
    if (childs[i].nodeType != 3) {
      str += childs[i].nodeName + " " + def + "<br />"
      str += getDef(childs[i], def + 1)
    }
  }

  return str
}


// Example
document.body.innerHTML = getDef(document.body, 0)

var tracker = {};
var depth = 0;
var prevNode;
Array.from(document.querySelectorAll("*")).forEach(node => {
    if (!tracker[node.tagName]) tracker[node.tagName] = 1;
    else tracker[node.tagName]++;
    console.log("Node depth:", node.tagName, depth);
    if (node.parentNode != prevNode) depth++;
    prevNode = node;
});
console.log(tracker);