hasclass，removeClass

var TH = TH || {};
TH.extend = function(first, second){
    for (var prop in second){
        first[prop] = second[prop];
    }
}; 
TH.css = function(element, styles){
    if (styles.opacity != null){
        if (typeof element.style.opacity != 'string' && typeof(element.filters) != 'undefined'){
            styles.filter = 'alpha(opacity=' + Math.round(100 * styles.opacity) + ')';
        }
    }
    TH.extend(element.style, styles);
};
TH.hasClass = function(element, name){
    var re = new RegExp('(^| )' + name + '( |$)');
    return re.test(element.className);
};
TH.addClass = function(element, name){
    if (!TH.hasClass(element, name)){
        element.className += ' ' + name;
    }
};
TH.removeClass = function(element, name){
    var re = new RegExp('(^| )' + name + '( |$)');
    element.className = element.className.replace(re, ' ').replace(/^\s+|\s+$/g, "");
};