client/views: extract empty view

...so that UsersController doesn't mess with DOM.

client/js/controllers/users_controller.js

@@ -9,11 +9,13 @@ const views = require('../util/views.js');
 const topNavController = require('../controllers/top_nav_controller.js');
 const RegistrationView = require('../views/registration_view.js');
 const UserView = require('../views/user_view.js');
+const EmptyView = require('../views/empty_view.js');
 
 class UsersController {
     constructor() {
         this.registrationView = new RegistrationView();
         this.userView = new UserView();
+        this.emptyView = new EmptyView();
     }
 
     registerRoutes() {
@@ -59,7 +61,7 @@ class UsersController {
                 this.user = response.user;
                 next();
             }).catch(response => {
-                views.emptyView(document.getElementById('content-holder'));
+                this.emptyView.render();
                 events.notify(events.Error, response.description);
             });
         }

client/js/util/views.js

@@ -84,12 +84,6 @@ function enableForm(form) {
     }
 }
 
-function emptyView(target) {
-    const ret = showView(target, htmlToDom('<div class="messages"></div>'));
-    listenToMessages(target);
-    return ret;
-}
-
 function showView(target, source) {
     return new Promise((resolve, reject) => {
         let observer = new MutationObserver(mutations => {
@@ -116,7 +110,6 @@ module.exports = {
     htmlToDom: htmlToDom,
     getTemplate: getTemplate,
     showView: showView,
-    emptyView: emptyView,
     enableForm: enableForm,
     disableForm: disableForm,
     listenToMessages: listenToMessages,

client/js/views/empty_view.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const views = require('../util/views.js');
+
+class EmptyView {
+    constructor() {
+        this.template = views.htmlToDom('<div class="messages"></div>');
+    }
+
+    render(ctx) {
+        const target = document.getElementById('content-holder');
+        const source = this.template;
+        views.listenToMessages(target);
+        views.showView(target, source);
+    }
+}
+
+module.exports = EmptyView;

client/js/views/help_view.js

@@ -19,16 +19,13 @@ class HelpView {
         const source = this.template();
 
         ctx.section = ctx.section || 'about';
-        if (!(ctx.section in this.sectionTemplates)) {
+        if (ctx.section in this.sectionTemplates) {
-            views.emptyView(target);
-            return;
-        }
-
             views.showView(
                 source.querySelector('.content'),
                 this.sectionTemplates[ctx.section]({
                     name: config.name,
                 }));
+        }
 
         const allItemsSelector = '[data-name]';
         for (let item of source.querySelectorAll(allItemsSelector)) {