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previousNode method (NodeIterator, TreeWalker)

Browser support:
9
Finds the previous node relative to the current node in the ordered list represented by the current NodeIterator object or in the tree represented by the current TreeWalker object. If it exists, it will be made the current node and returned, else the current node is retained and null is returned.
Note: The TreeWalker and NodeIterator objects and their previousNode methods are supported in Internet Explorer from version 9.
The NodeIterator object represents the result of the createNodeIterator method as an ordered list. The elements of the ordered list refer to the nodes in the document that fulfill the conditions specified for the createNodeIterator method. For further details, please see the page for the NodeIterator object.
The TreeWalker object represents the result of the createTreeWalker method as a tree. The elements of the resulting tree refer to the nodes in the document that fulfill the conditions specified for the createTreeWalker method. For further details, please see the page for the TreeWalker object.

Syntax:

object.previousNode ( );
You can find the related objects in the Supported by objects section below.

Return value:

Returns the node if found, else returns null.

Example HTML code 1:

This example illustrates the use of the previousNode method:
<head>
    <script type="text/javascript">
        function ElementChecker (node) {
            if (node.tagName.toLowerCase () == 'span') {
                return NodeFilter.FILTER_ACCEPT;
            }
            return NodeFilter.FILTER_SKIP;
        }

        function FindSectionsBackward () {
            var contElem = document.getElementById ("content");
            if (document.createTreeWalker) {
                walker = document.createTreeWalker (contElem, NodeFilter.SHOW_ELEMENT, ElementChecker, false);
                
                    // get the last matching node
                var node = walker.lastChild ();
                
                while (node) {
                    alert ("The contents of the section:\n " + node.innerHTML);
                    node = walker.previousNode ();
                }
            }
            else {
                alert ("Your browser does not support the createTreeWalker method!");
            }
        }
    </script>
</head>
<body>
    <div id="content">
        <span>
            <b>1. Section</b><br />
            <span>
                <b>1.1. Subsection</b><br />
            </span>
        </span>
        <span>
            <b>2.Section</b><br />
        </span>
    </div>

    <br /><br />
    <button onclick="FindSectionsBackward ()">Find the sections backward with the TreeWalker object</button>
</body>
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Supported by objects:

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