How can I make the input field empty after ajax submit?

Question

I implemented a chat system to my app.
It refreshes the list of comments partially when after new comment was submit.
So new added comment pops up without reloading whole page.

It's working fine but the problem is, it won't make input field empty(initialize) after submit :(

How can I make it empty if it succeeded at submitting?
5 seconds Auto-refreshing will be another issue that's preventing. So I have to care about it, too.

and If possible I want to pop up flash alert 'you cant spam' when the user tried to submit comment within 10 seconds.
Let's assume as if I'm trying to submit comment from Users#show page

views/users/show.html.erb

<%= javascript_tag do %>
    jQuery(document).ready(function () {
        refreshPartial();
        setInterval(refreshPartial, 5000)
    });


    function refreshPartial() {
      $.ajax({
        url: "<%= show_user_path(@user) %>/refresh_part",
        type: "GET",
        dataType: "script",
      });
    }
<% end %>
......
<span id="chat">
<%= render 'users/comment' %>
</span>
<%= render 'users/comment_input' %>

views/users/_comment.html.erb

<table>
  <tr>
    <th>ID</th>
    <th>PIC</th>
    <th>Body</th>
    <th>Subject</th>
    <th>Posted by</th>
    <th>Delete</th>
  </tr>

<% @comments.each do |comment| %>
  <tr id="<%= dom_id(comment) %>">
    <td><%= comment.id %></td>
    <td>
            <% if comment.comment_icon? %>
                <ul class="thumbnails">
                <%= image_tag(comment.comment_icon.url(:thumb),:height => 100, :width => 100, :style => 'border:3px double #545565;' ) %>
                </ul>
            <% end %>

    </td>
    <td><%= comment.body %></td>
    <td><%= comment.subject %></td>
    <td><%= comment.user.user_profile.nickname if comment.user.user_profile %></td>
    <td>
    <%= button_to 'destroy', polymorphic_path([@user, comment]), :data => {:confirm => 'Are you sure?'}, :method => :delete, :disable_with => 'deleting...', :remote => true, :class => 'btn btn-danger' if current_user && current_user.id == comment.user_id %>
    </td>
    </tr>
<% end %>
</table>

<%= paginate @comments, :window => 4, :outer_window => 5, :left => 2, :right => 2 %>

views/users/_comment_input.html.erb <= This is input form!!!!!

<%=form_for(([@user, @comment]), :remote => true) do |f| %>
    <div class="field">
      <%= f.label :body %><br />
      <%= f.text_field :body %>
    </div>
    <div class="field">
    <%= f.file_field :comment_icon %>
    </div>
  <div class="actions">
    <%= f.submit %>
  </div>

<% end %>

comments_controller.rb

def create
  commentable = @community_topic||@community||@user
  @comments = commentable.comment_threads.order("updated_at DESC").page(params[:page]).per(5)
  @comment = Comment.build_from(commentable, current_user.try(:id), params[:comment][:body]) 
  @comment.comment_icon = params[:comment][:comment_icon] 


  if @user
    @following_users = @user.all_following(order: 'updated_at DESC') 
    @followed_users = @user.followers 
    @communities_user = @user.get_up_voted(Community).order("updated_at ASC").page(params[:page]).per(5)
  elsif @community      

  end

  last_comment = Comment.where(:user_id => current_user.id).order("updated_at").last

  if last_comment && (Time.now - last_comment.updated_at) <= 10.second  
    flash[:notice] = "You cannot spam!" 
    render :template => template_for(commentable)
  elsif @comment.save 
    #if  @community_topic.empty?
        @comments = commentable.comment_threads.order("updated_at DESC").page(params[:page]).per(5)
        @comment = commentable.comment_threads.build

        respond_to do |format|
            format.html { redirect_to [@community, commentable].uniq, :notice => "comment added!"  }
            format.js do
                if @community.present?
                  render 'communities/refresh_part' 
                elsif @community_topic.present?
                  render 'community_topics/refresh_part'
                elsif @user.present?
                  render 'users/refresh_part'
                end
            end
        end 
  else
    render :template => template_for(commentable)
  end
end

views/users/refresh_part.js.erb

$('#chat').html("<%= j(render(:partial => 'users/comment')) %>")

Answer 1

Well I assume this is the "body" input you want to empty so basically, just add an id to it like this :

<%= f.text_field :body, :id => "body_input" %>

And in your views/users/refresh_part.js.erb , you can add something like :

$('#body_input').val('');

This should work only if it succeded at submitting because from what I saw, your template is rendered only if the comment is saved.