# Yahoo! UI Library

### TreeView Widget

Yahoo! UI Library > treeview > TVAnim.js (source view)

    /**
     * A static factory class for tree view expand/collapse animations
     * @class TVAnim
     * @static
     */
    YAHOO.widget.TVAnim = function() {
        return {
            /**
             * Constant for the fade in animation
             * @property FADE_IN
             * @type string
             * @static
             */
            FADE_IN: "TVFadeIn",

            /**
             * Constant for the fade out animation
             * @property FADE_OUT
             * @type string
             * @static
             */
            FADE_OUT: "TVFadeOut",

            /**
             * Returns a ygAnim instance of the given type
             * @method getAnim
             * @param type {string} the type of animation
             * @param el {HTMLElement} the element to element (probably the children div)
             * @param callback {function} function to invoke when the animation is done.
             * @return {YAHOO.util.Animation} the animation instance
             * @static
             */
            getAnim: function(type, el, callback) {
                if (YAHOO.widget[type]) {
                    return new YAHOO.widget[type](el, callback);
                } else {
                    return null;
                }
            },

            /**
             * Returns true if the specified animation class is available
             * @method isValid
             * @param type {string} the type of animation
             * @return {boolean} true if valid, false if not
             * @static
             */
            isValid: function(type) {
                return (YAHOO.widget[type]);
            }
        };
    } ();

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