gistfile1.js

/* Jquery plugin for quick Comet long polling connections
Nothing special about this (just a recursive Ajax call). 
The key is having the server hold connections open until there's data to push back to the client.
This can be done with Nginx and the nginx_http_push_module (http://github.com/slact/nginx_http_push_module)
---------------------------------------------------------------------------*/
(function($){
  $.comet = function(url, success_callback, error_callback){
    error_callback = error_callback || function(a,b,c){alert('Error '+b)};
    $.ajax({
      type: "GET",
      dataType: 'json',
      url: url,
      success: function(data){
        success_callback(data);
        $.comet(url, success_callback, error_callback);
      },
      error: function(a,b,c){
        error_callback(a,b,c);
        $.comet(url, success_callback, error_callback);
      },
      ifModified: true
    });
  }
})(jQuery);

/*
Usage
------------------------------------------------------*/
$.comet(function(data){
  $('#content').prepend(data.someAttribute)
});