add extended JSON subprotocol support

index.coffee

@@ -20,24 +20,58 @@ removeElement = (array, elem) ->
         index = array.indexOf(elem)
         array.splice(index, 1) if index > -1
 
-broadcastCounter = ->
-        sockets.forEach (socket) ->
-                socket.send counter
+makeHelloMsg = ->
+        return {
+                event: "hello",
+                features: [],
+                count: counter
+        }
 
-app.ws "/api", (ws, req) ->
-        ws.send counter
-        sockets.push ws
+makeCountMsg = ->
+        return {
+                event: "countUpdate",
+                count: counter
+        }
+
+broadcastCounter = ->
+        msg = makeCountMsg()
+        sockets.forEach (socket) ->
+                switch socket.protocol
+                        when "incdec" then socket.send counter
+                        when "extended-json" then socket.send JSON.stringify(msg)
+                        else socket.send counter
+
+setupExtendedSocket = (ws) ->
+        ws.send JSON.stringify(makeHelloMsg())
         ws.on "message", (msg) ->
-                switch
-                        when msg=="inc"
-                                counter = counter + 1
-                        when msg=="dec"
-                                counter = counter - 1
+                data = JSON.parse(msg)
+                switch data.event
+                        when "increment" then counter = counter + 1
+                        when "decrement" then counter = counter - 1
+                        else
+                                errored = true
+                                ws.close
+                broadcastCounter() if not errored
+        ws.on "close", -> removeElement sockets, ws
+
+setupSocket = (ws) ->
+        ws.send counter
+        ws.on "message", (msg) ->
+                switch msg
+                        when "inc" then counter = counter + 1
+                        when "dec" then counter = counter - 1
                         else
                                 errored = true
                                 ws.send "err"
                 broadcastCounter() if not errored
         ws.on "close", -> removeElement sockets, ws
+
+app.ws "/api", (ws, req) ->
+        sockets.push ws
+        switch ws.protocol
+                when "incdec" then setupSocket(ws)
+                when "extended-json" then setupExtendedSocket(ws)
+                else setupSocket(ws)
         
 app.listen config.port, () ->
         console.log("ready on port " + config.port)

static/app.coffee

@@ -1,12 +1,13 @@
 window.addEventListener "DOMContentLoaded", (event) ->
-         window.socket = new WebSocket(location.origin.replace(/^http/, "ws") + "/api")
+         window.socket = new WebSocket(location.origin.replace(/^http/, "ws") + "/api", "extended-json")
          counter = document.getElementById "counter"
 
          socket.addEventListener "message", (event) ->
-                 if event.data == "err"
-                         alert "error occured"
-                 else
-                         counter.innerText = event.data
+                 data = JSON.parse(event.data);
+                 switch data.event
+                         when "hello" then counter.innerText = data.count
+                         when "countUpdate" then counter.innerText = data.count
+                         else alert "unknown event"
 
-increment = -> socket.send("inc")
-decrement = -> socket.send("dec")
+increment = -> socket.send(JSON.stringify({"event": "increment"}))
+decrement = -> socket.send(JSON.stringify({"event": "decrement"}))