// show.html.erb

<%= form_for Message.new, :remote => true do |f| %>
                           <%= f.text_field :content, id: 'new_message' %>
                           <%= f.hidden_field :conversation_id, :value => @conversation.id %>
                           <%= f.hidden_field :user_id, :value => current_user.id %>
                           <%= f.submit "Send" %>
                         <% end %>


// MessageController.rb

    def create
            @message = Message.create(content: params[:message][:content], user_id: params[:message][:user_id])
            conversation = Conversation.find(params[:message][:conversation_id])
        conversation.messages << @message
            Pusher['some-channel'].trigger('my_event', {
          message: @message
        })
        end


// create.js.erb

var pusher = new Pusher('PUSHER KEY');
var channel = pusher.subscribe('some-channels');
  channel.bind('my_event', function(data) {
    $(".chats").append("<%= escape_javascript render(@message) %>");
});
$("#new_message")[0].reset();

var has_run = false;
if (has_run === false) {
  has_run = true;
  var pusher = new Pusher('PUSHER KEY');
  var channel = pusher.subscribe('some-channels');
    channel.bind('my_event', function(data) {
      $(".chats").append("<%= escape_javascript render(@message) %>");
  });
  $("#new_message")[0].reset();
}