课程作业描述很长时才显示更多按钮

app/views/courses/homework.html.erb

@@ -27,9 +27,20 @@
             <%= student_new_homework bid %>
         <% end %>
         <div class="cl"></div>
-        <p  id="bid_description_<%= bid.id%>" class="news_description mt5">
+        <script>
-          <%= textilizable bid, :description %>
+            $(function(){
-        <div class="news_foot c_red" onclick="bid_show_more_des(<%= bid.id%>);" style="cursor:pointer;">
+                if($("#bid_description_<%= bid.id%>_content").height()>38)
+                {
+                    $("#bid_show_more_des_button<%= bid.id%>").show();
+                }
+            });
+        </script>
+        <div  id="bid_description_<%= bid.id%>" class="news_description mt5">
+          <div id="bid_description_<%= bid.id%>_content">
+            <%= textilizable bid, :description %>
+          </div>
+        </div>
+        <div class="news_foot c_red" id="bid_show_more_des_button<%= bid.id%>" onclick="bid_show_more_des(<%= bid.id%>);" style="cursor:pointer;display: none;">
           <%= l(:button_more)%>...
           <span class="g-arr-down"></span>
         </div>

public/javascripts/course.js

@@ -34,10 +34,7 @@ function bid_show_more_des(id)
 {
     $("#bid_description_" + id).toggleClass("news_description_none");
 }
-//将右侧的最小高度设置成左侧高度，美化界面
+
-$(document).ready(function () {
-    $("#RSide").css("min-height",$("#LSide").height()-30);
-});
 //课程作业结束时间倒计时
 function show_bid_dead_line(year,month,day,divname)
 {
@@ -152,9 +149,15 @@ function hidden_atert_form(cur_page,cur_type)
     hideModal($("#popbox"));
 }
 
+//当课程描述长度小于112px时，不显示更多按钮
 $(function(){
     if($("#course_description_content").height()>112)
     {
         $("#lg-foot").show();
     }
+});
+
+//将右侧的最小高度设置成左侧高度，美化界面
+$(document).ready(function () {
+    $("#RSide").css("min-height",$("#LSide").height()-30);
 });