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    Document.createTreeWalker()

    The Document.createTreeWalker() creator method returns a newly created TreeWalker object.

    Syntax

    treeWalker = document.createTreeWalker(root, whatToShow, filter, entityReferenceExpansion);
    

    Parameters

    root
    Is the root Node of this TreeWalker traversal. Typically this will be an element owned by the document.
    whatToShow Optional
    Is an optional unsigned long representing a bitmask created by combining the constant properties of NodeFilter. It is a convenient way of filtering for certain types of node. It defaults to 0xFFFFFFFF representing the SHOW_ALL constant.
    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.
    filter Optional
    Is an optional NodeFilter, that is an object with a method acceptNode, which is called by the TreeWalker to determine whether or not to accept a node that has passed the whatToShow check.
    entityReferenceExpansion Optional
    Is a Boolean flag indicating if when discarding an EntityReference its whole sub-tree must be discarded at the same time.

    Example

    The following example goes through all nodes in the body, reduces the set of nodes to elements, simply passes through as acceptable each node (it could reduce the set in the acceptNode() method instead), and then makes use of tree walker iterator that is created to advance through the nodes (now all elements) and push them into an array.

    var treeWalker = document.createTreeWalker(
      document.body,
      NodeFilter.SHOW_ELEMENT,
      { acceptNode: function(node) { return NodeFilter.FILTER_ACCEPT; } },
      false
    );
    
    var nodeList = [];
    
    while(treeWalker.nextNode()) nodeList.push(treeWalker.currentNode);
    

    Specifications

    Specification Status Comment
    DOM
    The definition of 'Document.createTreeWalker' in that specification.
    Living Standard Removed the expandEntityReferences parameter.
    Made the whatToShow and filter parameters optionals.
    Document Object Model (DOM) Level 2 Traversal and Range Specification
    The definition of 'Document.createTreeWalker' in that specification.
    Recommendation Initial definition.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 1.0 2.0 (1.8.1) 9.0 9.0 3.0
    whatToShow and filter optional 1.0 12 (12) Not supported (Yes) 3.0
    expandEntityReferences 1.0 2.0 (1.8.1)
    Removed in 12 (12)
    9.0 9.0 3.0
    Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) 1.0 (1.8.1) (Yes) 9.0 3.0
    whatToShow and filter optional (Yes) 12 (12) Not supported (Yes) 3.0
    expandEntityReferences (Yes) 2.0 (1.8.1)
    Removed in 12 (12)
    (Yes) 9.0 3.0

    See also

    Document Tags and Contributors

    Last updated by: Pointy,
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