Issue #2939885 by samuel.mortenson: UX regression (again): Prevent links in node preview from being clicked

core/modules/node/node.libraries.yml

@@ -20,6 +20,7 @@ drupal.node.preview:
     - core/jquery
     - core/jquery.once
     - core/drupal
+    - core/drupal.dialog
     - core/drupal.form
 
 drupal.content_types:

core/modules/node/node.preview.es6.js

@@ -45,9 +45,9 @@
         }
       }
 
-      const $preview = $(context).find('.content').once('node-preview');
+      const $preview = $(context).once('node-preview');
       if ($(context).find('.node-preview-container').length) {
-        $preview.on('click.preview', 'a:not([href^=#], #edit-backlink, #toolbar-administration a)', clickPreviewModal);
+        $preview.on('click.preview', 'a:not([href^="#"], .node-preview-container a)', clickPreviewModal);
       }
     },
     detach(context, settings, trigger) {

core/modules/node/node.preview.js

@@ -29,9 +29,9 @@
         }
       }
 
-      var $preview = $(context).find('.content').once('node-preview');
+      var $preview = $(context).once('node-preview');
       if ($(context).find('.node-preview-container').length) {
-        $preview.on('click.preview', 'a:not([href^=#], #edit-backlink, #toolbar-administration a)', clickPreviewModal);
+        $preview.on('click.preview', 'a:not([href^="#"], .node-preview-container a)', clickPreviewModal);
       }
     },
     detach: function detach(context, settings, trigger) {

core/modules/node/tests/src/FunctionalJavascript/NodePreviewLinkTest.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Drupal\Tests\node\FunctionalJavascript;
+
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+
+/**
+ * Tests the JavaScript prevention of navigation away from node previews.
+ *
+ * @group node
+ */
+class NodePreviewLinkTest extends JavascriptTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['node', 'filter'];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+
+    $filtered_html_format = FilterFormat::create([
+      'format' => 'filtered_html',
+      'name' => 'Filtered HTML',
+    ]);
+    $filtered_html_format->save();
+
+    $this->drupalCreateContentType(['type' => 'test']);
+
+    $user = $this->drupalCreateUser([
+      'access content',
+      'edit own test content',
+      'create test content',
+      $filtered_html_format->getPermissionName(),
+    ]);
+    $this->drupalLogin($user);
+  }
+
+  /**
+   * Test the behavior of clicking preview links.
+   */
+  public function testPreviewLinks() {
+    $assertSession = $this->assertSession();
+    $this->drupalPostForm('node/add/test', [
+      'title[0][value]' => 'Test node',
+      'body[0][value]' => '<a href="#foo">Anchor link</a><a href="/foo">Normal link</a>',
+    ], t('Preview'));
+    $this->clickLink('Anchor link');
+    $assertSession->pageTextNotContains('Leave preview?');
+    $this->clickLink('Normal link');
+    $assertSession->pageTextContains('Leave preview?');
+    $this->click('button:contains("Leave preview")');
+    $this->assertStringEndsWith('/foo', $this->getUrl());
+  }
+
+}