How do you limit CoffeeScript (or JavaScript) execution to a particular controller and action in Rails 3.1?

Question

The new Rails 3.1 asset pipeline is really nice, but since all CoffeeScript (or JavaScript) files get melded down into a single file that is included in every page, it raise

Answer 1

If you are using the gon gem for your vars in coffee script you can use this pattern:

Put a flag for every action in the controller:

  def index
    @gps_coords = GpsCoord.all

    # Flag for the CoffeeScript to decide which part to run
    gon.index = true;
  end

  def show
    @gps_coord = GpsCoord.find(params[:id])

    gon.lat = @gps_coord.latitude
    gon.lon = @gps_coord.longitude

    gon.show = true;
  end

In the correlating coffee script use those flags to distiguish between the both actions:

  # index action?
  if gon.index? 
    first_coord = gon.gps_coords[0]
    map.setView([first_coord.latitude, first_coord.longitude], 15);

  # show action?
  if gon.show?
    map.setView([gon.lat, gon.lon], 15);