The Document.createNodeIterator() method returns a new NodeIterator object.

root

The root node at which to begin the NodeIterator's traversal.

whatToShow Optional

An optional 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.

Constant	Numerical value	Description
NodeFilter.SHOW_ALL	4294967295 (that is the max value of unsigned long)	Shows all nodes.
NodeFilter.SHOW_ATTRIBUTE Deprecated	2	Shows attribute Attr nodes. This is meaningful only when creating a TreeWalker 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 Deprecated	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 nodes.
NodeFilter.SHOW_ELEMENT	1	Shows Element nodes.
NodeFilter.SHOW_ENTITY Deprecated	32	Legacy, no more usable.
NodeFilter.SHOW_ENTITY_REFERENCE Deprecated	16	Legacy, no more usable.
NodeFilter.SHOW_NOTATION Deprecated	2048	Legacy, no more usable.
NodeFilter.SHOW_PROCESSING_INSTRUCTION	64	Shows ProcessingInstruction nodes.
NodeFilter.SHOW_TEXT	4	Shows Text nodes.

filter Optional

A callback function or an object with an acceptNode() method. The function or method will be called for each node in the subtree based at root which is accepted as included by the whatToShow flag to determine whether or not to include it in the list of iterable nodes. The method should return one of NodeFilter.FILTER_ACCEPT, NodeFilter.FILTER_REJECT, or NodeFilter.FILTER_SKIP. See the Example.

A new NodeIterator object.

const nodeIterator = document.createNodeIterator(
  document.body,
  NodeFilter.SHOW_ELEMENT,
  (node) =>
    node.nodeName.toLowerCase() === "p"
      ? NodeFilter.FILTER_ACCEPT
      : NodeFilter.FILTER_REJECT,
);
const pars = [];
let currentNode;

while ((currentNode = nodeIterator.nextNode())) {
  pars.push(currentNode);
}

The same, but using an object with an acceptNode() method:

const nodeIterator = document.createNodeIterator(
  document.body,
  NodeFilter.SHOW_ELEMENT,
  {
    acceptNode(node) {
      return node.nodeName.toLowerCase() === "p"
        ? NodeFilter.FILTER_ACCEPT
        : NodeFilter.FILTER_REJECT;
    },
  },
);
const pars = [];
let currentNode;

while ((currentNode = nodeIterator.nextNode())) {
  pars.push(currentNode);
}