Document.createTreeWalker()

document.createTreeWalker(root, whatToShow[, filter[, entityReferenceExpansion]]);

root

корневой узел Node для TreeWalker (en-US). Чаще всего это элемент принадлежащий document.

whatToShow Необязательный

A unsigned long representing a bitmask created by combining the constant properties of NodeFilter. It is a convenient way of filtering for certain types of node. It defaults to 0xFFFFFFFF representing the SHOW_ALL constant.

Константа	Числовое значение	Описание
NodeFilter.SHOW_ALL	-1 (that is the max value of unsigned long)	Показывать все узлы.
NodeFilter.SHOW_ATTRIBUTE Устарело	2	Shows attribute Attr nodes. This is meaningful only when creating a TreeWalker (en-US) with an Attr node as its root; in this case, it means that the attribute node will appear in the first position of the iteration or traversal. Since attributes are never children of other nodes, they do not appear when traversing over the document tree.
NodeFilter.SHOW_CDATA_SECTION Устарело	8	Shows CDATASection nodes.
NodeFilter.SHOW_COMMENT	128	Shows Comment nodes.
NodeFilter.SHOW_DOCUMENT	256	Shows Document nodes.
NodeFilter.SHOW_DOCUMENT_FRAGMENT	1024	Shows DocumentFragment nodes.
NodeFilter.SHOW_DOCUMENT_TYPE	512	Shows DocumentType (en-US) nodes.
NodeFilter.SHOW_ELEMENT	1	Shows Element nodes.
NodeFilter.SHOW_ENTITY Устарело	32	Shows Entity nodes. This is meaningful only when creating a TreeWalker (en-US) with an Entity node as its root; in this case, it means that the Entity node will appear in the first position of the traversal. Since entities are not part of the document tree, they do not appear when traversing over the document tree.
NodeFilter.SHOW_ENTITY_REFERENCE Устарело	16	Shows EntityReference nodes.
NodeFilter.SHOW_NOTATION Устарело	2048	Shows Notation nodes. This is meaningful only when creating a TreeWalker (en-US) with a Notation node as its root; in this case, it means that the Notation node will appear in the first position of the traversal. Since entities are not part of the document tree, they do not appear when traversing over the document tree.
NodeFilter.SHOW_PROCESSING_INSTRUCTION	64	Shows ProcessingInstruction (en-US) nodes.
NodeFilter.SHOW_TEXT	4	Shows Text nodes.

filter Необязательный

A NodeFilter (en-US), that is an object with a method acceptNode, which is called by the TreeWalker (en-US) to determine whether or not to accept a node that has passed the whatToShow check.

entityReferenceExpansion Необязательный

A Boolean (en-US) flag indicating if when discarding an EntityReference its whole sub-tree must be discarded at the same time.

A new TreeWalker (en-US) object.

The following example goes through all nodes in the body, reduces the set of nodes to elements, simply passes through as acceptable each node (it could reduce the set in the acceptNode() method instead), and then makes use of tree walker iterator that is created to advance through the nodes (now all elements) and push them into an array.

var treeWalker = document.createTreeWalker(
  document.body,
  NodeFilter.SHOW_ELEMENT,
  {
    acceptNode: function (node) {
      return NodeFilter.FILTER_ACCEPT;
    },
  },
  false,
);

var nodeList = [];

while (treeWalker.nextNode()) nodeList.push(treeWalker.currentNode);

• The interface of the object it creates: TreeWalker (en-US).