function hasClassName(node, class_name) {
    return new RegExp('\\b'+class_name+'\\b').test(node.className);
};

function addClassName(node, class_name) {
    if (!node.className) {
        node.className = class_name;
    } else if (!hasClassName(node, class_name)) {
        var className = node.className+" "+class_name;
        // cleanup
        node.className = className.split(/\s+/).join(' ');
    }
};

function removeClassName(node, class_name) {
    var className = node.className;
    if (className) {
        // remove
        className = className.replace(new RegExp('\\b'+class_name+'\\b'), '');
        // cleanup
        className = className.replace(/\s+/g, ' ');
        node.className = className.replace(/\s+$/g, '');
    }
};