Document the JavaScript classes

1 files changed, 45 insertions, 0 deletions

diff --git a/lib/assets/javascripts/cable/subscription.js.coffee b/lib/assets/javascripts/cable/subscription.js.coffee
index b60033098a..5b024d4e15 100644
--- a/lib/assets/javascripts/cable/subscription.js.coffee
+++ b/lib/assets/javascripts/cable/subscription.js.coffee
@@ -1,3 +1,48 @@
+# A new subscription is created through the Cable.Subscriptions instance available on the consumer. 
+# It provides a number of callbacks and a method for calling remote procedure calls on the corresponding 
+# Channel instance on the server side.
+#
+# An example demonstrates the basic functionality:
+#
+#   App.appearance = App.cable.subscriptions.create "AppearanceChannel",
+#     connected: ->
+#       # Called once the subscription has been successfully completed
+#   
+#     appear: ->
+#       @perform 'appear', appearing_on: @appearingOn()
+#   
+#     away: ->
+#       @perform 'away'
+#   
+#     appearingOn: ->
+#       $('main').data 'appearing-on'
+#
+# The methods #appear and #away forward their intent to the remote AppearanceChannel instance on the server
+# by calling the `@perform` method with the first parameter being the action (which maps to AppearanceChannel#appear/away).
+# The second parameter is a hash that'll get JSON encoded and made available on the server in the data parameter.
+#
+# This is how the server component would look:
+#
+#   class AppearanceChannel < ApplicationCable::Channel
+#     def subscribed
+#       current_user.appear
+#     end
+#   
+#     def unsubscribed
+#       current_user.disappear
+#     end
+#   
+#     def appear(data)
+#       current_user.appear on: data['appearing_on']
+#     end
+#   
+#     def away
+#       current_user.away
+#     end
+#   end
+#
+# The "AppearanceChannel" name is automatically mapped between the client-side subscription creation and the server-side Ruby class name.
+# The AppearanceChannel#appear/away public methods are exposed automatically to client-side invocation through the @perform method.
 class Cable.Subscription
   constructor: (@subscriptions, params = {}, mixin) ->
     @identifier = JSON.stringify(params)