Bug537 and Bug538

app/templates/login.html

@@ -1,7 +1,7 @@
 {% block body %}
 {% if session['logged_in'] %}
 
-你已登录 <a href="/{{ session['username'] }}">{{ session['username'] }}</a>。 登出点击<a href="/logout">这里</a>。
+你已登录 <a href="/{{ session['username'] }}/userpage">{{ session['username'] }}</a>。 登出点击<a href="/logout">这里</a>。
 
 {% else %}
 <meta charset="utf-8" name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />

app/templates/userpage_get.html

@@ -61,7 +61,7 @@
 {#    {% endfor %}#}
 
         <button class="btn btn-success" id="load_next_article" onclick="load_next_article();Reader.stopRead()"> 下一篇 Next Article </button>
-        <button class="btn btn-success" id="load_pre_article" onclick="load_pre_article();Reader.stopRead()" > 上一篇 Previous Article </button>
+        <button class="btn btn-success" id="load_pre_article" onclick="load_pre_article();Reader.stopRead()" style="display: none"> 上一篇 Previous Article </button>
 
     <p><b>阅读文章并回答问题</b></p>
     <div id="text-content">
@@ -162,6 +162,12 @@
     {% endfor %}
 {% endif %}
 <script type="text/javascript">
+    window.onload = function () { // 页面加载时执行
+        // 刷新页面或进入页面时判断，若不是首篇文章，则上一篇按钮可见
+        if(sessionStorage.getItem('pre_page_button')!="display" && sessionStorage.getItem('pre_page_button')){
+            $('#load_pre_article').show();
+        }
+     };
     function load_next_article(){
         $.ajax({
             url: '/get_next_article/{{username}}',
@@ -203,8 +209,10 @@
     function check_pre(visited_articles){
         if((visited_articles=='')||(visited_articles['index']<=0)){
             $('#load_pre_article').hide();
+            sessionStorage.setItem('pre_page_button', 'display')
         }else{
             $('#load_pre_article').show();
+            sessionStorage.setItem('pre_page_button', 'show')
         }
     }
     function check_next(result_of_generate_article){