关于页码的js代码

<script type="text/javascript">
            function submitMessageForm(flag) {
                if ('first' == flag) {
                    document.getElementById('page').value = 1;
                } else if ('pre' == flag) {
                    var current = Number(document.getElementById('page').value);
                    if (current > 1) {
                        document.getElementById('page').value = current - 1;
                    }
                } else if ('next' == flag) {
                    var current = Number(document.getElementById('page').value);
                    var last = Number(document.getElementById('last').value);
                    if (current < last) {
                        document.getElementById('page').value = current + 1;
                    }
                } else if ('last' == flag) {
                    var last = Number(document.getElementById('last').value);
                    document.getElementById('page').value = last < 1 ? 1 : last;
                }
                document.getElementById('messageForm').submit();
            }
        </script>

                <div id="pagefy">
                    <ul>
                        <form id="messageForm" action="${pageContext.request.contextPath}/message/list.do" method="post">
                            <input type="hidden" id="page" name="page" value="${page}">
                            <input type="hidden" id="last" name="last" value="${last}">
                            <li><a href="javascript:void(0)" onclick="submitMessageForm('first')">首页</a></li>
                            <li><a href="javascript:void(0)" onclick="submitMessageForm('pre')">上一页</a></li>
                            <li><a href="javascript:void(0)">当前第${page}页</a></li>
                            <li><a href="javascript:void(0)" onclick="submitMessageForm('next')">下一页</a></li>
                            <li><a href="javascript:void(0)" onclick="submitMessageForm('last')">尾页</a></li>
                        </form>
                    </ul>
                </div>