Web/API/TreeWalker

The TreeWalker object represents the nodes of a document subtree and a position within them.

A TreeWalker can be created using the Document.createTreeWalker() method.

Properties

This interface doesn't inherit any property.

TreeWalker.root Read only

Returns a Node representing the root node as specified when the TreeWalker was created.

TreeWalker.whatToShow Read only

Returns an unsigned long being a bitmask made of constants describing the types of Node that must be presented. Non-matching nodes are skipped, but their children may be included, if relevant. The possible values are:

Constant	Numerical value	Description
`NodeFilter.SHOW_ALL`	`-1` (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`	Shows `Entity` nodes. This is meaningful only when creating a `TreeWalker` 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` '	`16`	Shows `EntityReference` nodes.
`NodeFilter.SHOW_NOTATION` '	`2048`	Shows `Notation` nodes. This is meaningful only when creating a `TreeWalker` 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` nodes.
`NodeFilter.SHOW_TEXT`	`4`	Shows `Text` nodes.

TreeWalker.filter Read only

Returns a NodeFilter used to select the relevant nodes.

TreeWalker.expandEntityReferences Read only '

Is a Boolean indicating, when discarding an EntityReference its whole sub-tree must be discarded at the same time.

TreeWalker.currentNode

Is the Node on which the TreeWalker is currently pointing at.

Methods

This interface doesn't inherit any method.

Note: in the context of a TreeWalker, a node is visible if it exists in the logical view determined by the whatToShow and filter parameter arguments. (Whether or not the node is visible on the screen is irrelevant.)

TreeWalker.parentNode(): Moves the current Node to the first visible ancestor node in the document order, and returns the found node. It also moves the current node to this one. If no such node exists, or if it is before that the root node defined at the object construction, returns null and the current node is not changed.
TreeWalker.firstChild(): Moves the current Node to the first visible child of the current node, and returns the found child. It also moves the current node to this child. If no such child exists, returns null and the current node is not changed.
TreeWalker.lastChild(): Moves the current Node to the last visible child of the current node, and returns the found child. It also moves the current node to this child. If no such child exists, null is returned and the current node is not changed.
TreeWalker.previousSibling(): Moves the current Node to its previous sibling, if any, and returns the found sibling. If there is no such node, return null and the current node is not changed.
TreeWalker.nextSibling(): Moves the current Node to its next sibling, if any, and returns the found sibling. If there is no such node, null is returned and the current node is not changed.
TreeWalker.previousNode(): Moves the current Node to the previous visible node in the document order, and returns the found node. It also moves the current node to this one. If no such node exists, or if it is before that the root node defined at the object construction, returns null and the current node is not changed.
TreeWalker.nextNode(): Moves the current Node to the next visible node in the document order, and returns the found node. It also moves the current node to this one. If no such node exists, returns null and the current node is not changed.

Specifications

Specification	Status	Comment
DOMThe definition of 'TreeWalker' in that specification.	Living Standard	Removed the `expandEntityReferences` property.
Document Object Model (DOM) Level 2 Traversal and Range SpecificationThe definition of 'TreeWalker' in that specification.	Obsolete	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`TreeWalker`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`currentNode`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`expandEntityReferences` Deprecated'	Chrome Full support 1	Edge Full support 12	Firefox No support 4 — 21	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android No support 4 — 21	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`filter`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`firstChild`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`lastChild`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`nextNode`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`nextSibling`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`parentNode`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`previousNode`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`previousSibling`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`root`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes
`whatToShow`	Chrome Full support 1	Edge Full support 12	Firefox Full support 4	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 3	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3	Samsung Internet Android Full support Yes

Legend

Full support: Full support
No support: No support
Deprecated. Not for use in new websites.': Deprecated. Not for use in new websites.