ajax.coffee

class Ajax
  @getJSON: (url, event)->
    $.getJSON url, (data)->
      Event.trigger(event, data)

event.coffee

class Event
  @on: (event, fn)->
    $('body').bind event, (_, data) -> fn(data)

  @trigger: (event, data)->
    $('body').trigger(event, [data])

tracker.coffee

class Tracker
  @fetchAll: ->
    Ajax.getJSON "/current_positions", "trackers:ready"

  @fetchByUIN: (uin)->
    Ajax.getJSON "/trackers/#{uin}", "tracker:ready"