create isPageExist

src/client/js/services/PageContainer.js

@@ -60,12 +60,15 @@ export default class PageContainer extends Container {
       sumOfBookmarks: 0,
       createdAt: mainContent.getAttribute('data-page-created-at'),
       updatedAt: mainContent.getAttribute('data-page-updated-at'),
+
       isTrashPage: isTrashPage(path),
       isForbidden: JSON.parse(mainContent.getAttribute('data-page-is-forbidden')),
       isDeleted: JSON.parse(mainContent.getAttribute('data-page-is-deleted')),
       isDeletable: JSON.parse(mainContent.getAttribute('data-page-is-deletable')),
       isNotCreatable: JSON.parse(mainContent.getAttribute('data-page-is-not-creatable')),
       isAbleToDeleteCompletely: JSON.parse(mainContent.getAttribute('data-page-is-able-to-delete-completely')),
+      isPageExist: mainContent.getAttribute('data-page-id') != null,
+
       pageUser: JSON.parse(mainContent.getAttribute('data-page-user')),
       tags: null,
       hasChildren: JSON.parse(mainContent.getAttribute('data-page-has-children')),