public interface TreeWalker
TreeWalker
objects are used to navigate a document tree or
subtree using the view of the document defined by their
whatToShow
flags and filter (if any). Any function which
performs navigation using a TreeWalker
will automatically
support any view defined by a TreeWalker
.
Omitting nodes from the logical view of a subtree can result in a
structure that is substantially different from the same subtree in the
complete, unfiltered document. Nodes that are siblings in the
TreeWalker
view may be children of different, widely
separated nodes in the original view. For instance, consider a
NodeFilter
that skips all nodes except for Text nodes and
the root node of a document. In the logical view that results, all text
nodes will be siblings and appear as direct children of the root node, no
matter how deeply nested the structure of the original document.
See also the Document Object Model (DOM) Level 2 Traversal and Range Specification.
- Since:
- 9, DOM Level 2
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Method Summary
Modifier and TypeMethodDescriptionMoves theTreeWalker
to the first visible child of the current node, and returns the new node.The node at which theTreeWalker
is currently positioned.boolean
The value of this flag determines whether the children of entity reference nodes are visible to theTreeWalker
.The filter used to screen nodes.getRoot()
Theroot
node of theTreeWalker
, as specified when it was created.int
This attribute determines which node types are presented via theTreeWalker
.Moves theTreeWalker
to the last visible child of the current node, and returns the new node.nextNode()
Moves theTreeWalker
to the next visible node in document order relative to the current node, and returns the new node.Moves theTreeWalker
to the next sibling of the current node, and returns the new node.Moves to and returns the closest visible ancestor node of the current node.Moves theTreeWalker
to the previous visible node in document order relative to the current node, and returns the new node.Moves theTreeWalker
to the previous sibling of the current node, and returns the new node.void
setCurrentNode
(Node currentNode) The node at which theTreeWalker
is currently positioned.
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Method Details
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getRoot
Node getRoot()Theroot
node of theTreeWalker
, as specified when it was created. -
getWhatToShow
int getWhatToShow()This attribute determines which node types are presented via theTreeWalker
. The available set of constants is defined in theNodeFilter
interface. Nodes not accepted bywhatToShow
will be skipped, but their children may still be considered. Note that this skip takes precedence over the filter, if any. -
getFilter
NodeFilter getFilter()The filter used to screen nodes. -
getExpandEntityReferences
boolean getExpandEntityReferences()The value of this flag determines whether the children of entity reference nodes are visible to theTreeWalker
. If false, these children and their descendants will be rejected. Note that this rejection takes precedence overwhatToShow
and the filter, if any.
To produce a view of the document that has entity references expanded and does not expose the entity reference node itself, use thewhatToShow
flags to hide the entity reference node and setexpandEntityReferences
to true when creating theTreeWalker
. To produce a view of the document that has entity reference nodes but no entity expansion, use thewhatToShow
flags to show the entity reference node and setexpandEntityReferences
to false. -
getCurrentNode
Node getCurrentNode()The node at which theTreeWalker
is currently positioned.
Alterations to the DOM tree may cause the current node to no longer be accepted by theTreeWalker
's associated filter.currentNode
may also be explicitly set to any node, whether or not it is within the subtree specified by theroot
node or would be accepted by the filter andwhatToShow
flags. Further traversal occurs relative tocurrentNode
even if it is not part of the current view, by applying the filters in the requested direction; if no traversal is possible,currentNode
is not changed. -
setCurrentNode
The node at which theTreeWalker
is currently positioned.
Alterations to the DOM tree may cause the current node to no longer be accepted by theTreeWalker
's associated filter.currentNode
may also be explicitly set to any node, whether or not it is within the subtree specified by theroot
node or would be accepted by the filter andwhatToShow
flags. Further traversal occurs relative tocurrentNode
even if it is not part of the current view, by applying the filters in the requested direction; if no traversal is possible,currentNode
is not changed.- Throws:
DOMException
- NOT_SUPPORTED_ERR: Raised if an attempt is made to setcurrentNode
tonull
.
-
parentNode
Node parentNode()Moves to and returns the closest visible ancestor node of the current node. If the search forparentNode
attempts to step upward from theTreeWalker
'sroot
node, or if it fails to find a visible ancestor node, this method retains the current position and returnsnull
.- Returns:
- The new parent node, or
null
if the current node has no parent in theTreeWalker
's logical view.
-
firstChild
Node firstChild()Moves theTreeWalker
to the first visible child of the current node, and returns the new node. If the current node has no visible children, returnsnull
, and retains the current node.- Returns:
- The new node, or
null
if the current node has no visible children in theTreeWalker
's logical view.
-
lastChild
Node lastChild()Moves theTreeWalker
to the last visible child of the current node, and returns the new node. If the current node has no visible children, returnsnull
, and retains the current node.- Returns:
- The new node, or
null
if the current node has no children in theTreeWalker
's logical view.
-
previousSibling
Node previousSibling()Moves theTreeWalker
to the previous sibling of the current node, and returns the new node. If the current node has no visible previous sibling, returnsnull
, and retains the current node.- Returns:
- The new node, or
null
if the current node has no previous sibling. in theTreeWalker
's logical view.
-
nextSibling
Node nextSibling()Moves theTreeWalker
to the next sibling of the current node, and returns the new node. If the current node has no visible next sibling, returnsnull
, and retains the current node.- Returns:
- The new node, or
null
if the current node has no next sibling. in theTreeWalker
's logical view.
-
previousNode
Node previousNode()Moves theTreeWalker
to the previous visible node in document order relative to the current node, and returns the new node. If the current node has no previous node, or if the search forpreviousNode
attempts to step upward from theTreeWalker
'sroot
node, returnsnull
, and retains the current node.- Returns:
- The new node, or
null
if the current node has no previous node in theTreeWalker
's logical view.
-
nextNode
Node nextNode()Moves theTreeWalker
to the next visible node in document order relative to the current node, and returns the new node. If the current node has no next node, or if the search for nextNode attempts to step upward from theTreeWalker
'sroot
node, returnsnull
, and retains the current node.- Returns:
- The new node, or
null
if the current node has no next node in theTreeWalker
's logical view.
-