这应该是《精通javascript》中的例子。function getElementsByClass(object, tag, className) {var o = object.getElementsByTagName(tag);for ( var i = 0, n = o.length, ret = []; i < n; i++) {//定义用className获取对象的函数 if (o.className == className) ret.push(o);//当className为传入值，加入ret数组中}if (ret.length == 1) ret = ret[0];//如果
