Yahoo! UI Library

var addClass, hasClass, removeClass;

Y.mix(Y.DOM, {
    /**
     * Determines whether a DOM element has the given className.
     * @method hasClass
     * @param {HTMLElement} element The DOM element. 
     * @param {String} className the class name to search for
     * @return {Boolean} Whether or not the element has the given class. 
     */
    hasClass: function(node, className) {
        var re = Y.DOM._getRegExp('(?:^|\\s+)' + className + '(?:\\s+|$)');
        return re.test(node.className);
    },

    /**
     * Adds a class name to a given DOM element.
     * @method addClass         
     * @param {HTMLElement} element The DOM element. 
     * @param {String} className the class name to add to the class attribute
     */
    addClass: function(node, className) {
        if (!Y.DOM.hasClass(node, className)) { // skip if already present 
            node.className = Y.Lang.trim([node.className, className].join(' '));
        }
    },

    /**
     * Removes a class name from a given element.
     * @method removeClass         
     * @param {HTMLElement} element The DOM element. 
     * @param {String} className the class name to remove from the class attribute
     */
    removeClass: function(node, className) {
        if (className && hasClass(node, className)) {
            node.className = Y.Lang.trim(node.className.replace(Y.DOM._getRegExp('(?:^|\\s+)' +
                            className + '(?:\\s+|$)'), ' '));

            if ( hasClass(node, className) ) { // in case of multiple adjacent
                removeClass(node, className);
            }
        }                 
    },

    /**
     * Replace a class with another class for a given element.
     * If no oldClassName is present, the newClassName is simply added.
     * @method replaceClass  
     * @param {HTMLElement} element The DOM element. 
     * @param {String} oldClassName the class name to be replaced
     * @param {String} newClassName the class name that will be replacing the old class name
     */
    replaceClass: function(node, oldC, newC) {
        //Y.log('replaceClass replacing ' + oldC + ' with ' + newC, 'info', 'Node');
        addClass(node, newC);
        removeClass(node, oldC);
    },

    /**
     * If the className exists on the node it is removed, if it doesn't exist it is added.
     * @method toggleClass  
     * @param {HTMLElement} element The DOM element. 
     * @param {String} className the class name to be toggled
     */
    toggleClass: function(node, className) {
        if (hasClass(node, className)) {
            removeClass(node, className);
        } else {
            addClass(node, className);
        }
    }
});

hasClass = Y.DOM.hasClass;
removeClass = Y.DOM.removeClass;
addClass = Y.DOM.addClass;