TreeWalker: whatToShow property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The TreeWalker.whatToShow read-only property returns a bitmask that indicates the types of nodes to show. Non-matching nodes are skipped, but their children may be included, if relevant. The possible values are:

Constant Numerical value Description
NodeFilter.SHOW_ALL 4294967295 (that is the max value of unsigned long) Shows all nodes.
NodeFilter.SHOW_ATTRIBUTE 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 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 32 Legacy, no more used.
NodeFilter.SHOW_ENTITY_REFERENCE 16 Legacy, no more used.
NodeFilter.SHOW_NOTATION 2048 Legacy, no more used.
NodeFilter.SHOW_PROCESSING_INSTRUCTION 64 Shows ProcessingInstruction nodes.
NodeFilter.SHOW_TEXT 4 Shows Text nodes.

Value

A bitmask.

Examples

js
const treeWalker = document.createTreeWalker(
  document.body,
  NodeFilter.SHOW_ELEMENT + NodeFilter.SHOW_COMMENT + NodeFilter.SHOW_TEXT,
  { acceptNode: (node) => NodeFilter.FILTER_ACCEPT },
  false,
);
if (
  treeWalker.whatToShow === NodeFilter.SHOW_ALL ||
  treeWalker.whatToShow % (NodeFilter.SHOW_COMMENT * 2) >=
    NodeFilter.SHOW_COMMENT
) {
  // treeWalker will show comments
}

Specifications

Specification
DOM Standard
# dom-treewalker-whattoshow

Browser compatibility

BCD tables only load in the browser

See also