add locks on the MemoryService of the vue mvc example, keep it simple but runnable:P

Former-commit-id: 5d661f401e486a26d66f5c0c297f5cf897fc1834

_examples/tutorial/vuejs-todo-mvc/src/web/controllers/todo_controller.go

@@ -54,7 +54,7 @@ func (c *TodoController) Post(newItems []todo.Item) PostItemResponse {
 func (c *TodoController) GetSync(conn websocket.Connection) {
 	conn.Join(c.Session.ID())
 	conn.On("save", func() { // "save" event from client.
-		conn.To(c.Session.ID()).Emit("saved", nil) // fire a "save" event to the rest of the clients.
+		conn.To(c.Session.ID()).Emit("saved", nil) // fire a "saved" event to the rest of the clients w.
 	})
 
 	conn.Wait()

_examples/tutorial/vuejs-todo-mvc/src/web/main.go

@@ -21,28 +21,34 @@ func main() {
 	// back-end services, you can just stop afer this line and start the server.
 	app.StaticWeb("/", "./public")
 
+	// configure the http sessions.
 	sess := sessions.New(sessions.Config{
 		Cookie: "iris_session",
 	})
 
+	// configure the websocket server.
 	ws := websocket.New(websocket.Config{})
 
+	// create a sub router and register the client-side library for the iris websockets,
+	// you could skip it but iris websockets supports socket.io-like API.
+	todosRouter := app.Party("/todos")
+	// http://localhost:8080/todos/iris-ws.js
+	// serve the javascript client library to communicate with
+	// the iris high level websocket event system.
+	todosRouter.Any("/iris-ws.js", websocket.ClientHandler())
+
 	// create our mvc application targeted to /todos relative sub path.
-	m := mvc.New(app.Party("/todos"))
+	todosApp := mvc.New(todosRouter)
+
 	// any dependencies bindings here...
-	m.AddDependencies(
+	todosApp.AddDependencies(
 		todo.NewMemoryService(),
 		mvc.Session(sess),
 		ws.Upgrade,
 	)
 
-	// http://localhost:8080/iris-ws.js
-	// serve the javascript client library to communicate with
-	// the iris high level websocket event system.
-	m.Router.Any("/iris-ws.js", websocket.ClientHandler())
-
 	// controllers registration here...
-	m.Register(new(controllers.TodoController))
+	todosApp.Register(new(controllers.TodoController))
 
 	// start the web server at http://localhost:8080
 	app.Run(iris.Addr(":8080"), iris.WithoutVersionChecker)

_examples/tutorial/vuejs-todo-mvc/src/web/public/js/app.js

@@ -13,7 +13,7 @@ socket.On("saved", function () {
 
 function fetchTodos(onComplete) {
   axios.get("/todos").then(response => {
-    if (response.data == null) {
+    if (response.data === null) {
       return;
     }
 
@@ -65,7 +65,6 @@ var app = new Vue({
   // app initial state
   data: {
     todos: todoStorage.fetch(),
-    hasChanges: false,
     newTodo: '',
     editedTodo: null,
     visibility: 'all'