Question

I have the following code:

   def show
    @game = $site.new_game_of_type(params[:id])
    @game.start
  end

  def update_game_time
    render :partial => 'countdown', :layout => false
  end

and the countdown partial:

<div id=countdown> <%= @game.running_time %></div>

In show.html.erb I have:

Time: <div id="countdown"> </div>

<%= periodically_call_remote(:frequency => 0.5, 
   :update => 'countdown', :url => {:action => :update_game_time}) %>

I want to create a game in the page that is showed by show, so I will have lot of ajax moving there but the user will not click anywhere. All the actions of the controller would be called from Javascript.

I got an error of @game being nil. It is nil even in the method update_game_time
how can I make the @game variable to remain valid while the user is in that page?

Answer 1

Making a request to the server every 0.5 seconds is not such a good idea.

My suggestion is to load the running_time once and then use javascript to increase/decrease it.

Maybe you could do something like:

<div id=countdown><%= @game.running_time %></div>

in the view and then use some javascript on it, to update the timer:

window.onload = function() {
  var countdownDiv = document.getElementById('countdown');

  var timerValue = parseInt(countdownDiv.innerHTML); // assuming that your running_time is an int (seconds)

  var dateObj = new Date();

  dateObj.setTime( timerValue*1000 );
  countdownDiv.innerHTML = dateObj.getMinutes() + ":" + dateObj.getSeconds();

  var timer = setInterval("dispalyTimer()", 1000);

  dispalyTimer = function() {
    dateObj.setTime( ( (dateObj.getTime()/1000) + 1 )*1000 );
    countdownDiv.innerHTML = dateObj.getMinutes() + ":" + dateObj.getSeconds();
  }
}

This is just a basic example, but you get the point. Anyway it’s better than to make a request to the server every half of second, for a timer that can work very well on the client side too.