Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

Availability

DOM Level 2 Traversal

Properties

readonly boolean expandEntityReferences

Whether this NodeIterator traverses the
children of EntityReference nodes (in XML documents). The value is
specified as an argument to Document.createNodeIterator(
) when the NodeIterator is first created.

readonly

NodeFilter

filter

The node
filter function that was specified for this NodeIterator in the call
to Document.createNodeIterator( ).

readonly

Node

root

The root node
at which the NodeIterator begins iterating. The value of this
property is specified in the call to
Document.createNodeIterator( ).

readonly unsigned long whatToShow

A set of
bit flags (see NodeFilter for a list of valid flags)
that specifies what types of Document nodes this NodeIterator will
consider. If a bit is not set in this property, the corresponding
node type will always be ignored by this NodeIterator. Note that the
value of this property is specified in the call to
Document.createNodeIterator( ).

Methods

detach( )

"Detaches" this NodeIterator from its document so that
the implementation no longer needs to modify the NodeIterator when
the document is modified. Call this method when you are done using a
NodeIterator. After detach( ) has been called, any
calls to other NodeIterator methods will cause exceptions.

nextNode( )

Returns the next node in the filtered sequence of nodes represented
by this NodeIterator, or null if the NodeIterator
has already returned the last node.

previousNode( )

Returns the previous node in the filtered sequence of nodes
represented by this NodeIterator, or null if there
is no previous node.

Description

A NodeIterator represents the sequence of Document nodes that results
from traversing a document subtree in document source order and
filtering the nodes using a two-stage process. Create a NodeIterator
object with Document.createNodeIterator( ). Use
the nextNode( ) and previousNode(
) methods to iterate forward and backward through the
sequence of nodes. Call detach( ) when you are
done with a NodeIterator, unless you are sure that the NodeIterator
will be garbage collected before the document is modified. Note that
the properties of this interface are all read-only copies of the
arguments passed to Document.createNodeIterator(
).

To be returned by the nextNode( ) or
previousNode( ) methods, a node must pass two
filtration steps. First, the node type must be one of the types
specified by the whatToShow property. See
NodeFilter for a list of constants that can be combined
to specify the whatToShow argument to
Document.createNodeIterator( ). Next, if the
filter property is not null,
each node that passes the whatToShow test is
passed to the filter function specified by the
filter property. If this function returns
NodeFilter.FILTER_ACCEPT, the node is returned. If
it returns NodeFilter.FILTER_REJECT or
NodeFilter.FILTER_SKIP, the NodeIterator skips the
node. Note that when a node is rejected by either of these filtration
steps, it is only the node itself that is rejected; the children of
the node are not automatically rejected and are subject to the same
filtration steps.

NodeIterator objects remain valid even if the document tree they are
traversing is modified. The nextNode( ) and
previousNode( ) methods return nodes based on the
current state of the document, not the state of the document that
existed when the NodeIterator was created.

See Also

NodeFilter, TreeWalker; Chapter 17

Returned by

Document.createNodeIterator( )