diff --git a/Classes/Common/AbstractDocument.php b/Classes/Common/AbstractDocument.php
index 30150904a6..84b83d3bcf 100644
--- a/Classes/Common/AbstractDocument.php
+++ b/Classes/Common/AbstractDocument.php
@@ -534,7 +534,7 @@ abstract protected function setPreloadedDocument($preloadedDocument): bool;
      *
      * @return array
      */
-    public abstract function getAllFiles();
+    abstract public function getAllFiles(): array;
 
     /**
      * This is a singleton class, thus an instance must be created by this method
@@ -557,9 +557,10 @@ public static function &getInstance(string $location, array $settings = [], bool
         $iiif = null;
 
         if (!$forceReload) {
+            $instance = self::getDocumentCache($location);
             if (isset(self::$registry[$location])) {
                 return self::$registry[$location];
-            } elseif ($instance = self::getDocumentCache($location)) {
+            } elseif ($instance !== false) {
                 self::$registry[$location] = $instance;
                 return $instance;
             }
@@ -1393,7 +1394,7 @@ public function toArray($uriBuilder, array $config = [])
             ];
 
             foreach ($this->physicalStructureInfo[$this->physicalStructure[$page]]['files'] as $fileGrp => $fileId) {
-                if ($allFiles === null) {
+                if (!$allFiles) {
                     $file = [
                         'url' => $this->getFileLocation($fileId),
                         'mimetype' => $this->getFileMimeType($fileId),
@@ -1416,11 +1417,13 @@ public function toArray($uriBuilder, array $config = [])
                         ->reset()
                         ->setTargetPageUid($GLOBALS['TSFE']->id)
                         ->setCreateAbsoluteUri($forceAbsoluteUrl)
-                        ->setArguments([
-                            'eID' => 'tx_dlf_pageview_proxy',
-                            'url' => $file['url'],
-                            'uHash' => GeneralUtility::hmac($file['url'], 'PageViewProxy')
-                        ])
+                        ->setArguments(
+                            [
+                                'eID' => 'tx_dlf_pageview_proxy',
+                                'url' => $file['url'],
+                                'uHash' => GeneralUtility::hmac($file['url'], 'PageViewProxy')
+                            ]
+                        )
                         ->build();
                 }
 
diff --git a/Classes/Common/IiifManifest.php b/Classes/Common/IiifManifest.php
index 600785d976..6c177bf994 100644
--- a/Classes/Common/IiifManifest.php
+++ b/Classes/Common/IiifManifest.php
@@ -422,7 +422,7 @@ public function getFileMimeType(string $id): string
     /**
      * @see AbstractDocument::getAllFiles()
      */
-    public function getAllFiles()
+    public function getAllFiles(): array
     {
         $files = [];
         $canvases = $this->iiif->getDefaultCanvases();
diff --git a/Classes/Common/MetsDocument.php b/Classes/Common/MetsDocument.php
index 1742f795dd..45580e9cb9 100644
--- a/Classes/Common/MetsDocument.php
+++ b/Classes/Common/MetsDocument.php
@@ -261,7 +261,7 @@ public function getFileMimeType(string $id): string
     /**
      * @see AbstractDocument::getAllFiles()
      */
-    public function getAllFiles()
+    public function getAllFiles(): array
     {
         $files = [];
         $fileNodes = $this->mets->xpath('./mets:fileSec/mets:fileGrp/mets:file');
diff --git a/Classes/Controller/DocumentController.php b/Classes/Controller/DocumentController.php
index 8925b10728..8d4c9ab784 100644
--- a/Classes/Controller/DocumentController.php
+++ b/Classes/Controller/DocumentController.php
@@ -13,7 +13,6 @@
 namespace Kitodo\Dlf\Controller;
 
 use TYPO3\CMS\Core\Utility\GeneralUtility;
-use TYPO3\CMS\Core\Utility\MathUtility;
 
 /**
  * Provide document JSON for client side access
@@ -39,7 +38,7 @@ public function mainAction()
             // Quit without doing anything if required variables are not set.
             return;
         }
-        
+
         $this->setPage();
 
         $metadataUrl = null;
@@ -49,11 +48,13 @@ public function mainAction()
                 ->reset()
                 ->setTargetPageUid((int) $this->settings['targetPidMetadata'])
                 ->setCreateAbsoluteUri(true)
-                ->setArguments([
-                    'tx_dlf' => [
-                        'id' => $this->requestData['id'],
-                    ],
-                ])
+                ->setArguments(
+                    [
+                        'tx_dlf' => [
+                            'id' => $this->requestData['id'],
+                        ],
+                    ]
+                )
                 ->build();
         }
 
@@ -65,7 +66,7 @@ public function mainAction()
                 ? array_merge($imageFileGroups, $fulltextFileGroups)
                 : [],
         ];
-        $tx_dlf_loaded = [
+        $loaded = [
             'state' => [
                 'documentId' => $this->requestData['id'],
                 'page' => $this->requestData['page'],
@@ -83,7 +84,7 @@ public function mainAction()
 
         $docConfiguration = '
             window.addEventListener("DOMContentLoaded", function() {
-                const tx_dlf_loaded = ' . json_encode($tx_dlf_loaded) . ';
+                const tx_dlf_loaded = ' . json_encode($loaded) . ';
                 window.dispatchEvent(new CustomEvent("tx-dlf-documentLoaded", {
                     detail: {
                         docController: new dlfController(tx_dlf_loaded)
@@ -116,17 +117,21 @@ protected function getUrlTemplate()
         //       page: \d+
         //       double: 0|1
 
-        $make = function ($page, $double, $pagegrid) {
+        $make = function ($page, $double, $pageGrid) {
             $result = $this->uriBuilder->reset()
-                ->setTargetPageUid($GLOBALS['TSFE']->id)
+                ->setTargetPageUid($this->configurationManager->getContentObject()->data['pid'])
                 ->setCreateAbsoluteUri(!empty($this->settings['forceAbsoluteUrl']) ? true : false)
-                ->setArguments([
-                    'tx_dlf' => array_merge($this->requestData, [
-                        'page' => $page,
-                        'double' => $double,
-                        'pagegrid' => $pagegrid
-                    ]),
-                ])
+                ->setArguments(
+                    [
+                        'tx_dlf' => array_merge(
+                            $this->requestData, [
+                                'page' => $page,
+                                'double' => $double,
+                                'pagegrid' => $pageGrid
+                            ]
+                        ),
+                    ]
+                )
                 ->build();
 
             $cHashIdx = strpos($result, '&cHash=');
@@ -154,7 +159,7 @@ protected function getUrlTemplate()
 
             if ($first[$i] === '2') {
                 $placeholder = 'PAGE_NO';
-            } else if ($first[$i] === '1') {
+            } elseif ($first[$i] === '1') {
                 $placeholder = 'DOUBLE_PAGE';
             } else {
                 $placeholder = 'PAGE_GRID';
@@ -166,5 +171,4 @@ protected function getUrlTemplate()
 
         return $result;
     }
-
 }
diff --git a/Classes/Controller/MetadataController.php b/Classes/Controller/MetadataController.php
index 2947d91db6..c74d5dc7a9 100644
--- a/Classes/Controller/MetadataController.php
+++ b/Classes/Controller/MetadataController.php
@@ -375,7 +375,7 @@ private function parseMetadata(int $i, string $name, $value, array &$metadata) :
         }
     }
 
-     /**
+    /**
      * Get metadata for given id array.
      *
      * @access private
@@ -385,7 +385,8 @@ private function parseMetadata(int $i, string $name, $value, array &$metadata) :
      *
      * @return void
      */
-    private function getIds($toc, &$output) {
+    private function getIds($toc, &$output)
+    {
         foreach ($toc as $entry) {
             $output[$entry['id']] = true;
             if (is_array($entry['children'])) {
diff --git a/Resources/Public/JavaScript/PageView/Controller.js b/Resources/Public/JavaScript/PageView/Controller.js
index 163b07390a..60391fefd4 100644
--- a/Resources/Public/JavaScript/PageView/Controller.js
+++ b/Resources/Public/JavaScript/PageView/Controller.js
@@ -17,21 +17,21 @@ class dlfController {
         /** @private */
         this.doc = doc;
 
-        this.eventTarget.addEventListener('tx-dlf-stateChanged', this.onStateChanged.bind(this));
-        window.addEventListener('popstate', this.onPopState.bind(this));
+        this.eventTarget.addEventListener("tx-dlf-stateChanged", this.onStateChanged.bind(this));
+        window.addEventListener("popstate", this.onPopState.bind(this));
 
         // Set initial state, so that browser navigation also works initial page
         history.replaceState(/** @type {dlf.PageHistoryState} */({
-            type: 'tx-dlf-page-state',
+            type: "tx-dlf-page-state",
             ...this.doc.state
-        }), '');
+        }), "");
 
         this.updateMultiPage(this.simultaneousPages);
 
         if (doc.metadataUrl !== null) {
             this.metadataPromise = fetch(doc.metadataUrl)
-                .then(response => response.text())
-                .then(html => ({
+                .then((response) => response.text())
+                .then((html) => ({
                     htmlCode: html,
                 }));
         } else {
@@ -64,13 +64,16 @@ class dlfController {
 
     getVisiblePages(firstPageNo = this.doc.state.page) {
         const result = [];
+
         for (let i = 0; i < this.simultaneousPages; i++) {
             const pageNo = firstPageNo + i;
             const pageObj = this.doc.document.pages[pageNo - 1];
+
             if (pageObj !== undefined) {
                 result.push({ pageNo, pageObj });
             }
         }
+
         return result;
     }
 
@@ -95,6 +98,7 @@ class dlfController {
      */
     findFileByGroup(pageNo, fileGroups) {
         const pageObj = this.getPageByNo(pageNo);
+
         if (pageObj === undefined) {
             return;
         }
@@ -109,7 +113,7 @@ class dlfController {
      * @returns {dlf.ResourceLocator | undefined}
      */
     findFileByKind(pageNo, fileKind) {
-        return this.findFileByGroup(pageNo, this.doc.fileGroups[fileKind]);
+        return this.findFileByGroup(pageNo, this.doc.fileGroups[fileKind]); // eslint-disable-line
     }
 
     fetchMetadata() {
@@ -120,16 +124,14 @@ class dlfController {
      * @param {dlf.StateChangeDetail} detail
      */
     changeState(detail) {
-        // TODO(client-side): Consider passing full new state in stateChanged event,
-        //                    then reduce usage of currentPageNo and simultaneousPages properties
-
+        // TODO(client-side): Consider passing full new state in stateChanged event, then reduce usage of currentPageNo and simultaneousPages properties
         if (detail.page !== undefined) {
             this.doc.state.page = detail.page;
         }
         if (detail.simultaneousPages !== undefined) {
             this.doc.state.simultaneousPages = detail.simultaneousPages;
         }
-        document.body.dispatchEvent(new CustomEvent('tx-dlf-stateChanged', { detail }));
+        document.body.dispatchEvent(new CustomEvent("tx-dlf-stateChanged", { detail }));
     }
 
     /**
@@ -139,9 +141,10 @@ class dlfController {
      */
     changePage(pageNo) {
         const clampedPageNo = Math.max(1, Math.min(this.numPages, pageNo));
+
         if (clampedPageNo !== this.doc.state.page) {
             this.changeState({
-                source: 'navigation',
+                source: "navigation",
                 page: clampedPageNo,
             });
         }
@@ -150,18 +153,20 @@ class dlfController {
     /**
      * @param {number} pageNo
      * @param {boolean} pageGrid
+     * @returns {string}
      */
     makePageUrl(pageNo, pageGrid = false) {
         const doublePage = this.simultaneousPages >= 2 ? 1 : 0;
+
         return this.doc.urlTemplate
-            .replace(/DOUBLE_PAGE/, doublePage)
-            .replace(/PAGE_NO/, pageNo)
-            .replace(/PAGE_GRID/, pageGrid ? '1' : '0');
+            .replace(/DOUBLE_PAGE/u, doublePage)
+            .replace(/PAGE_NO/u, pageNo)
+            .replace(/PAGE_GRID/u, pageGrid ? "1" : "0");
     }
 
     /**
-     * @private
      * @param {dlf.StateChangeEvent} e
+     * @private
      */
     onStateChanged(e) {
         this.pushHistory(e);
@@ -172,54 +177,55 @@ class dlfController {
     }
 
     /**
-     * @private
      * @param {PopStateEvent} e
+     * @private
      */
     onPopState(e) {
-        if (e.state == null || e.state.type !== 'tx-dlf-page-state') {
+        if (e.state == null || e.state.type !== "tx-dlf-page-state") {
             return;
         }
 
         const state = /** @type {dlf.PageHistoryState} */(e.state);
+
         if (state.documentId !== this.doc.state.documentId) {
             return;
         }
 
         e.preventDefault();
         this.changeState({
-            'source': 'history',
-            'page': state.page === this.currentPageNo ? undefined : state.page,
-            'simultaneousPages': state.simultaneousPages === this.simultaneousPages ? undefined : state.simultaneousPages
+            "source": "history",
+            "page": state.page === this.currentPageNo ? undefined : state.page,
+            "simultaneousPages": state.simultaneousPages === this.simultaneousPages ? undefined : state.simultaneousPages
         });
     }
 
     /**
-     * @private
      * @param {dlf.StateChangeEvent} e
+     * @private
      */
     pushHistory(e) {
         // Avoid loop of pushState/dispatchEvent
-        if (e.detail.source === 'history') {
+        if (e.detail.source === "history") {
             return;
         }
 
         history.pushState(/** @type {dlf.PageHistoryState} */({
-            type: 'tx-dlf-page-state',
+            type: "tx-dlf-page-state",
             ...this.doc.state
-        }), '', this.makePageUrl(this.doc.state.page));
+        }), "", this.makePageUrl(this.doc.state.page));
     }
 
     /**
-     * @private
      * @param {number} simultaneousPages
+     * @private
      */
     updateMultiPage(simultaneousPages) {
         if (simultaneousPages === 1) {
-            document.body.classList.add('page-single');
-            document.body.classList.remove('page-double');
+            document.body.classList.add("page-single");
+            document.body.classList.remove("page-double");
         } else if (simultaneousPages === 2) {
-            document.body.classList.remove('page-single');
-            document.body.classList.add('page-double');
+            document.body.classList.remove("page-single");
+            document.body.classList.add("page-double");
         }
     }
 }
diff --git a/Resources/Public/JavaScript/PageView/Metadata.js b/Resources/Public/JavaScript/PageView/Metadata.js
index b1ad1b7ed4..5879eea5dc 100644
--- a/Resources/Public/JavaScript/PageView/Metadata.js
+++ b/Resources/Public/JavaScript/PageView/Metadata.js
@@ -41,7 +41,7 @@ class dlfMetadata {
         /** @protected */
         this.config = config;
 
-        this.docController.eventTarget.addEventListener('tx-dlf-stateChanged', () => {
+        this.docController.eventTarget.addEventListener("tx-dlf-stateChanged", () => {
             this.onStateChanged();
         });
 
@@ -54,9 +54,11 @@ class dlfMetadata {
     async fetchMetadata() {
         try {
             const metadata = await this.docController.fetchMetadata();
-            const element = document.createElement('div');
-            element.innerHTML = metadata.htmlCode;
-            const metadataContainer = element.querySelector('.dlf-metadata-container');
+            const element = document.createElement("div");
+
+            element.innerHTML = metadata.htmlCode; // eslint-disable-line
+            const metadataContainer = element.querySelector(".dlf-metadata-container");
+
             if (metadataContainer !== null) {
                 this.config.container.replaceWith(metadataContainer);
                 this.updateSectionVisibility();
@@ -78,10 +80,11 @@ class dlfMetadata {
      * @protected
      */
     updateSectionVisibility() {
-        document.querySelectorAll('[data-metadata-list][data-dlf-section]').forEach((element) => {
+        document.querySelectorAll("[data-metadata-list][data-dlf-section]").forEach((element) => {
             let isShown = false;
+
             for (const page of this.docController.getVisiblePages()) {
-                if (this.shouldShowSection(page.pageObj, element.getAttribute('data-dlf-section'))) {
+                if (this.shouldShowSection(page.pageObj, element.getAttribute("data-dlf-section"))) {
                     isShown = true;
                     break;
                 }
@@ -92,9 +95,10 @@ class dlfMetadata {
     }
 
     /**
-     * @protected
      * @param {dlf.PageObject} pageObj
      * @param {string} section
+     * @returns {boolean}
+     * @protected
      */
     shouldShowSection(pageObj, section) {
         switch (this.config.rootline) {
diff --git a/Resources/Public/JavaScript/PageView/Navigation.js b/Resources/Public/JavaScript/PageView/Navigation.js
index 3d3bdefb37..80468ba3d7 100644
--- a/Resources/Public/JavaScript/PageView/Navigation.js
+++ b/Resources/Public/JavaScript/PageView/Navigation.js
@@ -30,34 +30,34 @@ class dlfNavigation {
          */
         this.navigationButtons = {
             pageStepBack: {
-                button: document.querySelector('.page-step-back'),
+                button: document.querySelector(".page-step-back"),
                 getPage: (prevPageNo) => prevPageNo - this.getLongStep(),
             },
             pageBack: {
-                button: document.querySelector('.page-back'),
+                button: document.querySelector(".page-back"),
                 // When we're on second page in double-page mode, make sure the "back" button is still shown
                 getPage: (prevPageNo) => Math.max(1, prevPageNo - this.docController.simultaneousPages),
             },
             pageFirst: {
-                button: document.querySelector('.page-first'),
+                button: document.querySelector(".page-first"),
                 getPage: (prevPageNo) => 1,
             },
             pageStepForward: {
-                button: document.querySelector('.page-step-forward'),
+                button: document.querySelector(".page-step-forward"),
                 getPage: (prevPageNo) => prevPageNo + this.getLongStep(),
             },
             pageForward: {
-                button: document.querySelector('.page-forward'),
+                button: document.querySelector(".page-forward"),
                 getPage: (prevPageNo) => prevPageNo + this.docController.simultaneousPages,
             },
             pageLast: {
-                button: document.querySelector('.page-last'),
+                button: document.querySelector(".page-last"),
                 getPage: (prevPageNo) => this.docController.numPages - (this.docController.simultaneousPages - 1),
             },
         };
 
         /** @private */
-        this.pageSelect = document.querySelector('.page-select');
+        this.pageSelect = document.querySelector(".page-select");
 
         this.registerEvents();
         this.updateNavigationControls();
@@ -68,24 +68,27 @@ class dlfNavigation {
      */
     registerEvents() {
         for (const [key, value] of Object.entries(this.navigationButtons)) {
-            if (this.config.features[key]) {
-                value.button.addEventListener('click', (e) => {
+
+            if (this.config.features[key]) { // eslint-disable-line
+                value.button.addEventListener("click", (e) => {
                     e.preventDefault();
 
                     const pageNo = value.getPage(this.docController.currentPageNo);
+
                     this.docController.changePage(pageNo);
                 });
             }
         }
 
-        this.pageSelect.addEventListener('change', (e) => {
+        this.pageSelect.addEventListener("change", (e) => {
             e.preventDefault();
 
             const pageNo = Number(e.target.value);
+
             this.docController.changePage(pageNo);
         });
 
-        this.docController.eventTarget.addEventListener('tx-dlf-stateChanged', () => {
+        this.docController.eventTarget.addEventListener("tx-dlf-stateChanged", () => {
             this.onStateChanged();
         });
     }
@@ -101,8 +104,8 @@ class dlfNavigation {
      * Number of pages to jump in long step (e.g., 10 pages in single page mode
      * vs. 20 pages in double page mode).
      *
-     * @protected
      * @returns {number}
+     * @protected
      */
     getLongStep() {
         return this.config.basePageSteps * this.docController.simultaneousPages;
@@ -119,6 +122,7 @@ class dlfNavigation {
 
         for (const value of Object.values(this.navigationButtons)) {
             const btnPageNo = value.getPage(currentPageNo);
+
             this.toggleButtonDisabled(value.button, btnPageNo);
             this.updateUrl(value.button, btnPageNo);
             this.updateText(value.button);
@@ -132,42 +136,42 @@ class dlfNavigation {
     /**
      * Enable/disable the button depending on current page.
      *
-     * @param {button} Element
-     * @param {pageNo}
-     *
+     * @param {Element} button
+     * @param {number} pageNo
      * @private
      */
     toggleButtonDisabled(button, pageNo) {
-        const isBtnPageVisible = this.docController.getVisiblePages(pageNo).some(page => page.pageNo === this.docController.currentPageNo);
+        const isBtnPageVisible = this.docController.getVisiblePages(pageNo).some((page) => page.pageNo === this.docController.currentPageNo);
+
         if (!isBtnPageVisible && 1 <= pageNo && pageNo <= this.docController.numPages) {
-            button.classList.remove('disabled');
+            button.classList.remove("disabled");
         } else {
-            button.classList.add('disabled');
+            button.classList.add("disabled");
         }
     }
 
     /**
      * Update URLs of navigation button.
-     * 
-     * @param {button} Element
      *
+     * @param {Element} button
+     * @param {number} pageNo
      * @private
      */
     updateUrl(button, pageNo) {
-        button.setAttribute('href', this.docController.makePageUrl(pageNo));
+        button.setAttribute("href", this.docController.makePageUrl(pageNo));
     }
 
     /**
      * Update text of navigation button.
-     * 
-     * @param {button} Element
      *
+     * @param {Element} button
      * @private
      */
     updateText(button) {
-        const textTemplate = button.getAttribute('data-text');
+        const textTemplate = button.getAttribute("data-text");
+
         if (textTemplate) {
-            button.textContent = textTemplate.replace(/PAGE_STEPS/, this.getLongStep());
+            button.textContent = textTemplate.replace(/PAGE_STEPS/u, this.getLongStep());
         }
     }
 }
diff --git a/Resources/Public/JavaScript/PageView/PageView.js b/Resources/Public/JavaScript/PageView/PageView.js
index e8fb660cc3..16984f52bd 100644
--- a/Resources/Public/JavaScript/PageView/PageView.js
+++ b/Resources/Public/JavaScript/PageView/PageView.js
@@ -17,12 +17,11 @@
 
 /**
  * @typedef {{
- *  div: string;
- *  progressElementId?: string;
- *  images?: dlf.ImageDesc[] | [];
- *  fulltexts?: dlf.FulltextDesc[] | [];
- *  controls?: ('OverviewMap' | 'ZoomPanel')[];
- *  initDoc: dlf.Document;
+ * div: string;
+ * progressElementId?: string;
+ * images?: dlf.ImageDesc[] | [];
+ * fulltexts?: dlf.FulltextDesc[] | [];
+ * controls?: ('OverviewMap' | 'ZoomPanel')[];
  * }} DlfViewerConfig
  *
  * @typedef {any} DlfDocument
@@ -90,7 +89,7 @@ var dlfViewer = function(settings){
      * @type {JQueryStatic.Deferred[]}
      * @private
      */
-    this.fulltextsLoaded_ = {};
+    this.fulltextsLoaded = {};
 
     /**
      * IIIF annotation lists URLs for the current canvas
@@ -188,7 +187,7 @@ var dlfViewer = function(settings){
      * Cache of promises / jQuery Deferred returned by `initLayer()`.
      * This has two benefits:
      * - Switching to a page that has already been visited is basically instantaneous.
-     *   When relying on browser cache, there still is a flicker.
+     * When relying on browser cache, there still is a flicker.
      * - It may allow to prefetch pages that are likely to be visited next (TODO(client-side): do that).
      *
      * @type {Record<string, JQueryStatic.Deferred>}
@@ -196,11 +195,6 @@ var dlfViewer = function(settings){
      */
     this.layersCache = {};
 
-    /**
-     * @private
-     */
-    this.initDoc = settings.initDoc;
-
     /**
      * @type {dlfController | null}
      * @private
@@ -297,7 +291,7 @@ dlfViewer.prototype.countPages = function () {
  *
  * @param {JQueryStatic.Deferred | undefined} currentFulltext
  */
-dlfViewer.prototype.updateFulltext = function (currentFulltext) {
+dlfViewer.prototype.updateFulltext = function(currentFulltext) {
     if (!this.fulltextControl) {
         this.fulltextControl = new dlfViewerFullTextControl(this.map);
     }
@@ -305,18 +299,18 @@ dlfViewer.prototype.updateFulltext = function (currentFulltext) {
         this.fulltextDownloadControl = new dlfViewerFullTextDownloadControl(this.map);
     }
     if (currentFulltext !== undefined && this.images.length === 1) {
-        $('#tx-dlf-tools-fulltext').show();
+        $("#tx-dlf-tools-fulltext").show();
 
         currentFulltext
-            .then( (fulltextData) => {
+            .then((fulltextData) => {
                 this.fulltextControl.loadFulltextData(fulltextData);
                 this.fulltextDownloadControl.setFulltextData(fulltextData);
             })
-            .catch( () => {
+            .catch(() => {
                 this.fulltextControl.deactivate();
             });
     } else {
-        $('#tx-dlf-tools-fulltext').hide();
+        $("#tx-dlf-tools-fulltext").hide();
         this.fulltextControl.deactivate();
     }
 };
@@ -328,33 +322,28 @@ dlfViewer.prototype.updateFulltext = function (currentFulltext) {
  * @param {Array.<string>} controlNames
  */
 dlfViewer.prototype.addCustomControls = function() {
-    var annotationControl = undefined,
-        imageManipulationControl = undefined,
-        images = this.images;
+    var annotationControl = undefined;
+    var imageManipulationControl = undefined;
 
     // Adds fulltext behavior and download only if there is fulltext available and no double page
     // behavior is active
-	const currentFulltext = this.fulltextsLoaded_[`${this.getVisiblePages()[0].pageNo}-0`];
+    const currentFulltext = this.fulltextsLoaded[`${this.getVisiblePages()[0].pageNo}-0`];
+
     this.updateFulltext(currentFulltext);
 
-    if (this.annotationContainers[0] !== undefined && this.annotationContainers[0].annotationContainers !== undefined
-        && this.annotationContainers[0].annotationContainers.length > 0 && this.images.length === 1) {
+    if (this.annotationContainers[0] !== undefined && this.annotationContainers[0].annotationContainers !== undefined && this.annotationContainers[0].annotationContainers.length > 0 && this.images.length === 1) {
         // Adds annotation behavior only if there are annotations available and view is single page
         annotationControl = new DlfAnnotationControl(this.map, this.images[0], this.annotationContainers[0]);
         if (this.fulltextControl !== undefined) {
             $(this.fulltextControl).on("activate-fulltext", $.proxy(annotationControl.deactivate, annotationControl));
             $(annotationControl).on("activate-annotations", $.proxy(this.fulltextControl.deactivate, this.fulltextControl));
         }
-    }
-    else {
-        $('#tx-dlf-tools-annotations').remove();
+    } else {
+        $("#tx-dlf-tools-annotations").remove();
     }
 
-    //
     // Add image manipulation tool if container is added.
-    //
-    if ($('#tx-dlf-tools-imagetools').length > 0) {
-
+    if ($("#tx-dlf-tools-imagetools").length > 0) {
         // should be called if cors is enabled
         imageManipulationControl = new dlfViewerImageManipulationControl({
             controlTarget: $('.tx-dlf-tools-imagetools')[0],
@@ -527,7 +516,7 @@ dlfViewer.prototype.displayHighlightWord = function(highlightWords = null) {
         var self = this;
         var values = decodeURIComponent(this.highlightWords).split(';');
 
-		const currentFulltext = this.fulltextsLoaded_[this.getVisiblePages()[0].pageNo];
+		const currentFulltext = this.fulltextsLoaded[this.getVisiblePages()[0].pageNo];
         $.when.apply($, currentFulltext)
             .done(function (fulltextData, fulltextDataImageTwo) {
                 var stringFeatures = [];
@@ -653,10 +642,9 @@ dlfViewer.prototype.init = function(controlNames) {
 
 dlfViewer.prototype.getVisiblePages = function () {
     if (this.docController === null) {
-        return this.initDoc.pages.map( (page, i) => ({
-            pageNo: this.initDoc.query.minPage + i,
-            pageObj: page
-        }));
+        /* eslint no-console: ["error", { allow: ["warn", "error"] }] */
+        console.error("No document controller found");
+        return;
     } else {
         return this.docController.getVisiblePages();
     }
@@ -713,7 +701,7 @@ dlfViewer.prototype.loadPages = function (visiblePages) {
 
             let i = 0;
             for (const page of pages) {
-                this.updateFulltext(this.fulltextsLoaded_[`${page.pageNo}-${i}`]);
+                this.updateFulltext(this.fulltextsLoaded[`${page.pageNo}-${i}`]);
                 i++;
             }
         });
@@ -755,14 +743,13 @@ dlfViewer.prototype.initLayer = function (imageSourceObjs) {
 };
 
 /**
- * Start loading fulltexts and store them to `fulltextsLoaded_` (as jQuery deferred objects).
+ * Start loading fulltexts and store them to `fulltextsLoaded` (as jQuery deferred objects).
  *
  * @param {dlf.PageObject[]} visiblePages
  * @private
  */
 dlfViewer.prototype.initLoadFulltexts = function (visiblePages) {
     if (this.docController === null) {
-        // TODO(client-side): Make it work then docController === null
         return;
     }
 
@@ -774,8 +761,8 @@ dlfViewer.prototype.initLoadFulltexts = function (visiblePages) {
 
         const fulltext = this.docController.findFileByKind(visiblePages[i].pageNo, 'fulltext');
         if (fulltext !== undefined) {
-            if (!(key in this.fulltextsLoaded_) && dlfUtils.isFulltextDescriptor(fulltext)) {
-                this.fulltextsLoaded_[key] = dlfFullTextUtils.fetchFullTextDataFromServer(fulltext.url, image, xOffset);
+            if (!(key in this.fulltextsLoaded) && dlfUtils.isFulltextDescriptor(fulltext)) {
+                this.fulltextsLoaded[key] = dlfFullTextUtils.fetchFullTextDataFromServer(fulltext.url, image, xOffset);
             }
         } else {
             /* eslint no-console: ["error", { allow: ["warn", "error"] }] */
diff --git a/Resources/Public/JavaScript/PageView/TableOfContents.js b/Resources/Public/JavaScript/PageView/TableOfContents.js
index 90611e4b68..38eb6a98f5 100644
--- a/Resources/Public/JavaScript/PageView/TableOfContents.js
+++ b/Resources/Public/JavaScript/PageView/TableOfContents.js
@@ -23,32 +23,35 @@ class dlfTableOfContents {
         /** @private */
         this.docController = docController;
         /** @private */
-        this.tocItems = document.querySelectorAll('[data-toc-item]');
+        this.tocItems = document.querySelectorAll("[data-toc-item]");
         /** @private */
-        this.tocLinks = document.querySelectorAll('[data-toc-link]');
+        this.tocLinks = document.querySelectorAll("[data-toc-link]");
 
         this.tocLinks.forEach((link) => {
-            const documentId = link.getAttribute('data-document-id');
+            const documentId = link.getAttribute("data-document-id");
+
             if (documentId && documentId !== this.docController.documentId) {
                 return;
             }
 
-            const pageNo = Number(link.getAttribute('data-page'));
-            link.addEventListener('click', e => {
+            const pageNo = Number(link.getAttribute("data-page"));
+
+            link.addEventListener("click", (e) => {
                 e.preventDefault();
                 this.docController.changePage(pageNo);
             });
         });
 
-        docController.eventTarget.addEventListener('tx-dlf-stateChanged', this.onStateChanged.bind(this));
+        docController.eventTarget.addEventListener("tx-dlf-stateChanged", this.onStateChanged.bind(this));
     }
 
     /**
-     * @private
      * @param {dlf.StateChangeEvent} e
+     * @private
      */
     onStateChanged(e) {
         const activeLogSections = [];
+
         // TODO(client-side): Add toplevel sections
         for (const page of this.docController.getVisiblePages()) {
             activeLogSections.push(...page.pageObj.logSections);
@@ -59,17 +62,20 @@ class dlfTableOfContents {
         // See TableOfContentsController::getMenuEntry()
         this.tocItems.forEach((tocItem) => {
             let tocItemState = dlfTocState.Normal;
-            let isExpanded = Boolean(tocItem.getAttribute('data-toc-expand-always'));
+            let isExpanded = Boolean(tocItem.getAttribute("data-toc-expand-always"));
+
+            const isCurrent = activeLogSections.includes(tocItem.getAttribute("data-dlf-section"));
 
-            const isCurrent = activeLogSections.includes(tocItem.getAttribute('data-dlf-section'));
             if (isCurrent) {
                 tocItemState = dlfTocState.Current;
             }
 
-            const children = Array.from(tocItem.querySelectorAll('[data-toc-item]'));
+            const children = Array.from(tocItem.querySelectorAll("[data-toc-item]"));
+
             if (children.length > 0 && isCurrent) {
                 // TODO(client-side): check depth?
-                const isActive = children.some(tocItemChild => activeLogSections.includes(tocItemChild.getAttribute('data-dlf-section')));
+                const isActive = children.some((tocItemChild) => activeLogSections.includes(tocItemChild.getAttribute("data-dlf-section")));
+
                 if (isActive) {
                     tocItemState = dlfTocState.Active;
                 }
@@ -78,27 +84,27 @@ class dlfTableOfContents {
             }
 
             if (tocItemState === dlfTocState.Normal) {
-                tocItem.classList.add('tx-dlf-toc-no');
+                tocItem.classList.add("tx-dlf-toc-no");
             } else {
-                tocItem.classList.remove('tx-dlf-toc-no');
+                tocItem.classList.remove("tx-dlf-toc-no");
             }
 
             if (tocItemState === dlfTocState.Active) {
-                tocItem.classList.add('active', 'tx-dlf-toc-act');
+                tocItem.classList.add("active", "tx-dlf-toc-act");
             } else {
-                tocItem.classList.remove('active', 'tx-dlf-toc-act');
+                tocItem.classList.remove("active", "tx-dlf-toc-act");
             }
 
             if (tocItemState === dlfTocState.Current) {
-                tocItem.classList.add('current', 'tx-dlf-toc-cur');
+                tocItem.classList.add("current", "tx-dlf-toc-cur");
             } else {
-                tocItem.classList.remove('current', 'tx-dlf-toc-cur');
+                tocItem.classList.remove("current", "tx-dlf-toc-cur");
             }
 
             if (isExpanded) {
-                tocItem.classList.remove('dlf-toc-collapsed');
+                tocItem.classList.remove("dlf-toc-collapsed");
             } else {
-                tocItem.classList.add('dlf-toc-collapsed');
+                tocItem.classList.add("dlf-toc-collapsed");
             }
 
             // "submenu" class does not change
diff --git a/Resources/Public/JavaScript/PageView/Toolbox.js b/Resources/Public/JavaScript/PageView/Toolbox.js
index 0852849c40..8ad4fcfcfe 100644
--- a/Resources/Public/JavaScript/PageView/Toolbox.js
+++ b/Resources/Public/JavaScript/PageView/Toolbox.js
@@ -17,15 +17,15 @@ class dlfToolbox {
         /** @private */
         this.docController = docController;
         /** @private */
-        this.pageLinks = document.querySelectorAll('[data-page-link]');
+        this.pageLinks = document.querySelectorAll("[data-page-link]");
 
-        docController.eventTarget.addEventListener('tx-dlf-stateChanged', this.onStateChanged.bind(this));
+        docController.eventTarget.addEventListener("tx-dlf-stateChanged", this.onStateChanged.bind(this));
         this.updatePageLinks(this.docController.currentPageNo);
     }
 
     /**
-     * @private
      * @param {dlf.StateChangeEvent} e
+     * @private
      */
     onStateChanged(e) {
         if (e.detail.page !== undefined) {
@@ -34,21 +34,20 @@ class dlfToolbox {
     }
 
     /**
-     * @private
      * @param {number} firstPageNo
+     * @private
      */
     updatePageLinks(firstPageNo) {
-        this.pageLinks.forEach(element => {
-            const offset = Number(element.getAttribute('data-page-link'));
+        this.pageLinks.forEach((element) => {
+            const offset = Number(element.getAttribute("data-page-link"));
             const pageNo = firstPageNo + offset;
 
             const fileGroups = this.getFileGroups(element);
-            const file = fileGroups !== null
-                ? this.docController.findFileByGroup(pageNo, fileGroups)
-                : this.docController.findFileByKind(pageNo, 'download');
+            const file = fileGroups !== null ? this.docController.findFileByGroup(pageNo, fileGroups) : this.docController.findFileByKind(pageNo, "download");
 
             if (file === undefined) {
                 $(element).hide();
+
                 return;
             }
             $(element).show();
@@ -56,22 +55,24 @@ class dlfToolbox {
             if (element instanceof HTMLAnchorElement) {
                 element.href = file.url;
             } else {
-                element.querySelectorAll('a').forEach(linkEl => {
+                element.querySelectorAll("a").forEach((linkEl) => {
                     linkEl.href = file.url;
                 });
             }
 
-            const mimetypeLabelEl = element.querySelector('.dlf-mimetype-label');
+            const mimetypeLabelEl = element.querySelector(".dlf-mimetype-label");
+
             if (mimetypeLabelEl !== null) {
                 // Transliterated from ToolboxController
-                let mimetypeLabel = '';
+                let mimetypeLabel = "";
+
                 switch (file.mimetype) {
-                    case 'image/jpeg':
-                        mimetypeLabel = ' (JPG)';
+                    case "image/jpeg":
+                        mimetypeLabel = " (JPG)";
                         break;
 
-                    case 'image/tiff':
-                        mimetypeLabel = ' (TIFF)';
+                    case "image/tiff":
+                        mimetypeLabel = " (TIFF)";
                         break;
                 }
 
@@ -81,15 +82,17 @@ class dlfToolbox {
     }
 
     /**
-     * @private
      * @param {Element} element
-     * @return {string[] | null}
+     * @returns {string[] | null}
+     * @private
      */
     getFileGroups(element) {
-        const fileGroupsJson = element.getAttribute('data-file-groups');
+        const fileGroupsJson = element.getAttribute("data-file-groups");
+
         try {
             const fileGroups = JSON.parse(fileGroupsJson);
-            if (Array.isArray(fileGroups) && fileGroups.every(entry => typeof entry === 'string')) {
+
+            if (Array.isArray(fileGroups) && fileGroups.every((entry) => typeof entry === "string")) {
                 return fileGroups;
             }
         } catch (e) {
diff --git a/Resources/Public/JavaScript/PageView/types.d.ts b/Resources/Public/JavaScript/PageView/types.d.ts
index 147c8b43c6..beb010f096 100644
--- a/Resources/Public/JavaScript/PageView/types.d.ts
+++ b/Resources/Public/JavaScript/PageView/types.d.ts
@@ -28,7 +28,7 @@ namespace dlf {
         simultaneousPages: number;
     };
 
-    type FileKind = 'images' | 'fulltext' | 'download';
+    type FileKind = "images" | "fulltext" | "download";
 
     type Loaded = {
         state: PageDisplayState;
@@ -38,23 +38,23 @@ namespace dlf {
         document: Document;
     };
 
-    type StateChangeEvent = CustomEvent<StateChangeDetail>;
-
     type StateChangeDetail = {
         /**
          * Who triggered the event.
          * * `history`: Event is triggered due to history popstate. This is used
-         *   to avoid pushing a popped state again.
+         * to avoid pushing a popped state again.
          * * `navigation`: Event is triggered by user navigation.
          */
-        source: 'history' | 'navigation';
+        source: "history" | "navigation";
     } & Partial<PageDisplayState>;
 
+    type StateChangeEvent = CustomEvent<StateChangeDetail>;
+
     /**
      * State of document stored in `window.history`.
      */
     type PageHistoryState = {
-        type: 'tx-dlf-page-state';
+        type: "tx-dlf-page-state";
         documentId: string | number;
     } & PageDisplayState;
 }