jQuery添加请求问题

Question

I have a database in which I add new records using Ajax requests and it works fine. By far I wrote a request which is adding properly new records right after already existing ones. I don't know what methods to use to add a new record when database is empty. How could adding request look like in my case? I'm sorry I'm only the beginner to Javascript. Thanks in advance.

views/tasks/create.js

$('.tasks').last().after("<%=j render partial: 'task', :locals => { :task => @task } %>");

views/tasks/_task.html partial

<tr class='tasks' id="task_<%= task.id %>">
  <td>
    <%= link_to user_task_path(current_user, task.id), method: :delete,
     data: { confirm: 'Are you sure?' }, remote: true do %>
      <i class="glyphicon glyphicon-trash"></i>
    <% end %>

    <a href="#" data-xeditable="true" data-pk="task" data-model='task' data-name='title'
      data-url="/users/<%= current_user.id %>/tasks/<%= task.id %>" data-title="Enter title">
      <i><%= task.title %></i>
    </a>

  </td>
</tr>

Here's my view file views/tasks/index.html file

   <h3>Tasks database</h3>

<table>
<% @tasks.each do |task| %>
<tr class='tasks' id="task_<%= task.id %>">
  <td>
    <%= link_to user_task_path(current_user, task.id), method: :delete,
     data: { confirm: 'Are you sure?' }, remote: true do %>
      <i class="glyphicon glyphicon-trash"></i>
    <% end %>

    <a href="#" data-xeditable="true" data-pk="task" data-model='task' data-name='title'
      data-url="/users/<%= current_user.id %>/tasks/<%= task.id %>" data-title="Enter title">
      <i><%= task.title %></i>
    </a>

  </td>
</tr>
<% end %>

<tr>
  <td><%= render 'form' %></td>
</tr>

</table>

Answer 1

You can check if there are any .tasks present, and act accordingly

var tasks = $('.tasks');

if ( tasks.length > 0 ) {
    tasks.last().after("<%=j render partial: 'task', :locals => { :task => @task } %>");
} else {
    $('table').prepend("<%=j render partial: 'task', :locals => { :task => @task } %>")
}