function hasClass(obj, cls) {

        if (obj.className) {

            return obj.className.match(new RegExp('(\\s|^)' + cls + '(\\s|$)'));

        }

        return false;

    }

    function addClass(obj, cls) {

        if (!hasClass(obj, cls)) obj.className += " " + cls;

    }

    function removeClass(obj, cls) {

        if (hasClass(obj, cls)) {

            var reg = new RegExp('(\\s|^)' + cls + '(\\s|$)');

            obj.className = obj.className.replace(reg, ' ');

        }

    }

    function removeAllClass(obj) {

        obj.className = '';

    }