function getElementsByClassName(element, names) {   //获取class元素
        if (element.getElementsByClassName) {
            return element.getElementsByClassName(names);
        } else {
            var elements = element.getElementsByTagName('*');
            var result = [];
            var element,
                classNameStr,
                flag;
            names = names.split(' ');
            for (var i = 0; element = elements[i]; i++) {
                classNameStr = ' ' + element.className + ' ';
                flag = true;
                for (var j = 0, name; name = names[j]; j++) {
                    if (classNameStr.indexOf(' ' + name + '') == -1) {
                        flag = false;
                        break;
                    }
                }
                if (flag) {
                    result.push(element);
                }
            }
            return result;
        }
}
请问在这段代码中element.getElementsByClassName这句话代表什么？