client/routing: fix certain history bug

The bug could be reproduced as follows:

1. Navigate to /posts
2. Search for "test"
3. Navigate to /posts again
4. Refresh the page

The user should see plain post list, but instead they were seeing the
"test" search results again as if step 3 never happened.

client/js/controllers/post_list_controller.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const config = require('../config.js');
+const router = require('../router.js');
 const api = require('../api.js');
 const settings = require('../models/settings.js');
 const uri = require('../util/uri.js');
@@ -54,9 +55,7 @@ class PostListController {
     }
 
     _evtNavigate(e) {
-        history.pushState(
-            null,
-            window.title,
+        router.showNoDispatch(
             uri.formatClientLink('posts', e.detail.parameters));
         Object.assign(this._ctx.parameters, e.detail.parameters);
         this._syncPageController();

client/js/controllers/tag_list_controller.js

@@ -1,5 +1,6 @@
 'use strict';
 
+const router = require('../router.js');
 const api = require('../api.js');
 const uri = require('../util/uri.js');
 const TagList = require('../models/tag_list.js');
@@ -46,9 +47,7 @@ class TagListController {
     }
 
     _evtNavigate(e) {
-        history.pushState(
-            null,
-            window.title,
+        router.showNoDispatch(
             uri.formatClientLink('tags', e.detail.parameters));
         Object.assign(this._ctx.parameters, e.detail.parameters);
         this._syncPageController();

client/js/controllers/user_list_controller.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const api = require('../api.js');
+const router = require('../router.js');
 const uri = require('../util/uri.js');
 const UserList = require('../models/user_list.js');
 const topNavigation = require('../models/top_navigation.js');
@@ -38,9 +39,7 @@ class UserListController {
     }
 
     _evtNavigate(e) {
-        history.pushState(
-            null,
-            window.title,
+        router.showNoDispatch(
             uri.formatClientLink('users', e.detail.parameters));
         Object.assign(this._ctx.parameters, e.detail.parameters);
         this._syncPageController();

client/js/router.js

@@ -158,6 +158,13 @@ class Router {
         window.removeEventListener('popstate', this._onPopState, false);
     }
 
+    showNoDispatch(path, state) {
+        const ctx = new Context(path, state);
+        ctx.pushState();
+        this.ctx = ctx;
+        return ctx;
+    }
+
     show(path, state, push) {
         const ctx = new Context(path, state);
         const oldPath = this.ctx ? this.ctx.path : ctx.path;