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.
Instance properties
This interface doesn't inherit any property.
TreeWalker.root
Read only-
Returns a
Node
representing the root node as specified when theTreeWalker
was created. TreeWalker.whatToShow
Read only-
Returns an
unsigned long
being a bitmask made of constants describing the types ofNode
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
4294967295
(that is the max value ofunsigned long
)Shows all nodes. NodeFilter.SHOW_ATTRIBUTE
Deprecated2
Shows attribute Attr
nodes. This is meaningful only when creating aTreeWalker
with anAttr
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
Deprecated8
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
Deprecated32
Legacy, no more usable. NodeFilter.SHOW_ENTITY_REFERENCE
Deprecated16
Legacy, no more usable. NodeFilter.SHOW_NOTATION
Deprecated2048
Legacy, no more usable. 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.currentNode
-
Is the
Node
on which theTreeWalker
is currently pointing at.
Instance 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, returnsnull
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, returnsnull
and the current node is not changed. Note that the node returned byfirstChild()
is dependent on the value ofwhatToShow
set during instantiation of theTreeWalker
object. Assuming the following HTML tree, and if you set thewhatToShow
toNodeFilter.SHOW_ALL
a call tofirstChild()
will return aText
node and not anHTMLDivElement
object.html
<!DOCTYPE html> <html lang="en"> <head><title>Demo</title> <body> <div id="container"></div> </body> </html>
js
let walker = document.createTreeWalker(document.body, NodeFilter.SHOW_ALL); let node = walker.firstChild(); // nodeName: "#text"
But if we do:
js
let walker = document.createTreeWalker( document.body, NodeFilter.SHOW_ELEMENT ); let node = walker.firstChild(); // nodeName: "DIV"
The same applies to
nextSibling()
,previousSibling()
,firstChild()
andlastChild()
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, returnnull
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, returnsnull
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, returnsnull
and the current node is not changed.
Specifications
Specification |
---|
DOM Standard # interface-treewalker |
Browser compatibility
BCD tables only load in the browser
See also
- The creator method:
Document.createTreeWalker()
. - Related interfaces:
NodeFilter
,NodeIterator
.