# Yahoo! UI Library

### TreeView Widget 2.8.1

Yahoo! UI Library > treeview > RootNode.js (source view)
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    /**
     * A custom YAHOO.widget.Node that handles the unique nature of
     * the virtual, presentationless root node.
     * @namespace YAHOO.widget
     * @class RootNode
     * @extends YAHOO.widget.Node
     * @param oTree {YAHOO.widget.TreeView} The tree instance this node belongs to
     * @constructor
     */
    YAHOO.widget.RootNode = function(oTree) {
        // Initialize the node with null params.  The root node is a
        // special case where the node has no presentation.  So we have
        // to alter the standard properties a bit.
        this.init(null, null, true);

        /*
         * For the root node, we get the tree reference from as a param
         * to the constructor instead of from the parent element.
         */
        this.tree = oTree;
    };

    YAHOO.extend(YAHOO.widget.RootNode, YAHOO.widget.Node, {

       /**
         * The node type
         * @property _type
          * @type string
         * @private
         * @default "RootNode"
         */
        _type: "RootNode",

        // overrides YAHOO.widget.Node
        getNodeHtml: function() {
            return "";
        },

        toString: function() {
            return this._type;
        },

        loadComplete: function() {
            this.tree.draw();
        },

       /**
         * Count of nodes in tree.
        * It overrides Nodes.getNodeCount because the root node should not be counted.
         * @method getNodeCount
         * @return {int} number of nodes in the tree
         */
        getNodeCount: function() {
            for (var i = 0, count = 0;i< this.children.length;i++) {
                count += this.children[i].getNodeCount();
            }
            return count;
        },

      /**
         * Returns an object which could be used to build a tree out of this node and its children.
         * It can be passed to the tree constructor to reproduce this node as a tree.
         * Since the RootNode is automatically created by treeView,
         * its own definition is excluded from the returned node definition
         * which only contains its children.
         * @method getNodeDefinition
         * @return {Object | false}  definition of the tree or false if any child node is defined as dynamic
         */
        getNodeDefinition: function() {

            for (var def, defs = [], i = 0; i < this.children.length;i++) {
                def = this.children[i].getNodeDefinition();
                if (def === false) { return false;}
                defs.push(def);
            }
            return defs;
        },

        collapse: function() {},
        expand: function() {},
        getSiblings: function() { return null; },
        focus: function () {}

    });

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