diff --git a/.eslintrc.json b/.eslintrc.json
index 0fe6743c..297f7500 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -178,6 +178,7 @@
                 "ext/js/comm/clipboard-monitor.js",
                 "ext/js/comm/clipboard-reader.js",
                 "ext/js/comm/mecab.js",
+                "ext/js/data/anki-util.js",
                 "ext/js/data/database.js",
                 "ext/js/data/json-schema.js",
                 "ext/js/data/options-util.js",
diff --git a/ext/action-popup.html b/ext/action-popup.html
index 03c94846..d5e8ee22 100644
--- a/ext/action-popup.html
+++ b/ext/action-popup.html
@@ -88,6 +88,7 @@
 
 <script src="/js/comm/api.js"></script>
 <script src="/js/comm/cross-frame-api.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/data/permissions-util.js"></script>
 <script src="/js/input/hotkey-help-controller.js"></script>
 <script src="/js/input/hotkey-util.js"></script>
diff --git a/ext/background.html b/ext/background.html
index c04ed7c1..4ce7ddf0 100644
--- a/ext/background.html
+++ b/ext/background.html
@@ -31,6 +31,7 @@
 <script src="/js/comm/clipboard-monitor.js"></script>
 <script src="/js/comm/clipboard-reader.js"></script>
 <script src="/js/comm/mecab.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/data/database.js"></script>
 <script src="/js/data/json-schema.js"></script>
 <script src="/js/data/options-util.js"></script>
diff --git a/ext/info.html b/ext/info.html
index 78210baf..d3bd3400 100644
--- a/ext/info.html
+++ b/ext/info.html
@@ -64,6 +64,7 @@
 
 <script src="/js/comm/api.js"></script>
 <script src="/js/comm/cross-frame-api.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/data/permissions-util.js"></script>
 <script src="/js/dom/document-focus-controller.js"></script>
 <script src="/js/dom/html-template-collection.js"></script>
diff --git a/ext/js/comm/anki.js b/ext/js/comm/anki.js
index 251e0e0c..da234eff 100644
--- a/ext/js/comm/anki.js
+++ b/ext/js/comm/anki.js
@@ -15,6 +15,10 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/* global
+ * AnkiUtil
+ */
+
 class AnkiConnect {
     constructor() {
         this._enabled = false;
@@ -113,7 +117,7 @@ class AnkiConnect {
                     query = `"deck:${this._escapeQuery(note.deckName)}" `;
                     break;
                 case 'deck-root':
-                    query = `"deck:${this._escapeQuery(this.getRootDeckName(note.deckName))}" `;
+                    query = `"deck:${this._escapeQuery(AnkiUtil.getRootDeckName(note.deckName))}" `;
                     break;
             }
             query += this._fieldsToQuery(note.fields);
@@ -138,11 +142,6 @@ class AnkiConnect {
         return await this.findCards(`nid:${noteId}`);
     }
 
-    getRootDeckName(deckName) {
-        const index = deckName.indexOf('::');
-        return index >= 0 ? deckName.substring(0, index) : deckName;
-    }
-
     // Private
 
     async _checkVersion() {
diff --git a/ext/js/data/anki-note-builder.js b/ext/js/data/anki-note-builder.js
index e1399f66..f12846b1 100644
--- a/ext/js/data/anki-note-builder.js
+++ b/ext/js/data/anki-note-builder.js
@@ -16,13 +16,14 @@
  */
 
 /* global
+ * AnkiUtil
  * TemplateRendererProxy
  */
 
 class AnkiNoteBuilder {
-    constructor(enabled) {
-        this._markerPattern = /\{([\w-]+)\}/g;
-        this._templateRenderer = enabled ? new TemplateRendererProxy() : null;
+    constructor() {
+        this._markerPattern = AnkiUtil.cloneFieldMarkerPattern(true);
+        this._templateRenderer = new TemplateRendererProxy();
     }
 
     async createNote({
@@ -46,7 +47,7 @@ class AnkiNoteBuilder {
         let duplicateScopeCheckChildren = false;
         if (duplicateScope === 'deck-root') {
             duplicateScope = 'deck';
-            duplicateScopeDeckName = this.getRootDeckName(deckName);
+            duplicateScopeDeckName = AnkiUtil.getRootDeckName(deckName);
             duplicateScopeCheckChildren = true;
         }
 
@@ -89,27 +90,6 @@ class AnkiNoteBuilder {
         };
     }
 
-    containsMarker(fields, marker) {
-        marker = `{${marker}}`;
-        for (const [, fieldValue] of fields) {
-            if (fieldValue.includes(marker)) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    containsAnyMarker(field) {
-        const result = this._markerPattern.test(field);
-        this._markerPattern.lastIndex = 0;
-        return result;
-    }
-
-    getRootDeckName(deckName) {
-        const index = deckName.indexOf('::');
-        return index >= 0 ? deckName.substring(0, index) : deckName;
-    }
-
     // Private
 
     async _formatField(field, data, templates, errors=null) {
diff --git a/ext/js/data/anki-util.js b/ext/js/data/anki-util.js
new file mode 100644
index 00000000..fc081ddc
--- /dev/null
+++ b/ext/js/data/anki-util.js
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2021  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * This class has some general utility functions for working with Anki data.
+ */
+class AnkiUtil {
+    /**
+     * Gets the root deck name of a full deck name. If the deck is a root deck,
+     * the same name is returned. Nested decks are separated using '::'.
+     * @param deckName A string of the deck name.
+     * @returns A string corresponding to the name of the root deck.
+     */
+    static getRootDeckName(deckName) {
+        const index = deckName.indexOf('::');
+        return index >= 0 ? deckName.substring(0, index) : deckName;
+    }
+
+    /**
+     * Checks whether or not any marker is contained in a string.
+     * @param string A string to check.
+     * @return `true` if the text contains an Anki field marker, `false` otherwise.
+     */
+    static stringContainsAnyFieldMarker(string) {
+        const result = this._markerPattern.test(string);
+        this._markerPattern.lastIndex = 0;
+        return result;
+    }
+
+    /**
+     * Gets a list of all markers that are contained in a string.
+     * @param string A string to check.
+     * @return An array of marker strings.
+     */
+    static getFieldMarkers(string) {
+        const pattern = this._markerPattern;
+        const markers = [];
+        while (true) {
+            const match = pattern.exec(string);
+            if (match === null) { break; }
+            markers.push(match[1]);
+        }
+        return markers;
+    }
+
+    /**
+     * Checks whether an object of key-value pairs has a value which contains a specific marker.
+     * @param fieldsObject An object with key-value pairs, where the value corresponds to the field value.
+     * @param marker The marker string to check for, excluding brackets.
+     * @returns `true` if any of the fields contains the marker, `false` otherwise.
+     */
+    static fieldsObjectContainsMarker(fieldsObject, marker) {
+        marker = `{${marker}}`;
+        for (const [, fieldValue] of fieldsObject) {
+            if (fieldValue.includes(marker)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Returns a regular expression which can be used to find markers in a string.
+     * @param global Whether or not the regular expression should have the global flag.
+     * @returns A new `RegExp` instance.
+     */
+    static cloneFieldMarkerPattern(global) {
+        return new RegExp(this._markerPattern.source, global ? 'g' : '');
+    }
+}
+
+// eslint-disable-next-line no-underscore-dangle
+AnkiUtil._markerPattern = /\{([\w-]+)\}/g;
diff --git a/ext/js/data/permissions-util.js b/ext/js/data/permissions-util.js
index bd3a18ce..3a5b5de5 100644
--- a/ext/js/data/permissions-util.js
+++ b/ext/js/data/permissions-util.js
@@ -15,13 +15,16 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/* global
+ * AnkiUtil
+ */
+
 class PermissionsUtil {
     constructor() {
         this._ankiFieldMarkersRequiringClipboardPermission = new Set([
             'clipboard-image',
             'clipboard-text'
         ]);
-        this._ankiMarkerPattern = /\{([\w-]+)\}/g;
     }
 
     hasPermissions(permissions) {
@@ -69,7 +72,7 @@ class PermissionsUtil {
     }
 
     getRequiredPermissionsForAnkiFieldValue(fieldValue) {
-        const markers = this._getAnkiFieldMarkers(fieldValue);
+        const markers = AnkiUtil.getFieldMarkers(fieldValue);
         const markerPermissions = this._ankiFieldMarkersRequiringClipboardPermission;
         for (const marker of markers) {
             if (markerPermissions.has(marker)) {
@@ -99,7 +102,7 @@ class PermissionsUtil {
             ];
             for (const fields of fieldsList) {
                 for (const fieldValue of Object.values(fields)) {
-                    const markers = this._getAnkiFieldMarkers(fieldValue);
+                    const markers = AnkiUtil.getFieldMarkers(fieldValue);
                     for (const marker of markers) {
                         if (fieldMarkersRequiringClipboardPermission.has(marker)) {
                             return false;
@@ -111,16 +114,4 @@ class PermissionsUtil {
 
         return true;
     }
-
-    // Private
-
-    _getAnkiFieldMarkers(fieldValue) {
-        const pattern = this._ankiMarkerPattern;
-        const markers = [];
-        let match;
-        while ((match = pattern.exec(fieldValue)) !== null) {
-            markers.push(match[1]);
-        }
-        return markers;
-    }
 }
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index 517b391d..0e029748 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -17,6 +17,7 @@
 
 /* global
  * AnkiNoteBuilder
+ * AnkiUtil
  * DisplayAudio
  * DisplayGenerator
  * DisplayHistory
@@ -85,7 +86,7 @@ class Display extends EventDispatcher {
         });
         this._ankiFieldTemplates = null;
         this._ankiFieldTemplatesDefault = null;
-        this._ankiNoteBuilder = new AnkiNoteBuilder(true);
+        this._ankiNoteBuilder = new AnkiNoteBuilder();
         this._updateAdderButtonsPromise = Promise.resolve();
         this._contentScrollElement = document.querySelector('#content-scroll');
         this._contentScrollBodyElement = document.querySelector('#content-body');
@@ -1493,7 +1494,7 @@ class Display extends EventDispatcher {
         const definitionDetails = this._getDefinitionDetailsForNote(definition);
 
         let audioDetails = null;
-        if (definitionDetails.type !== 'kanji' && this._ankiNoteBuilder.containsMarker(fields, 'audio')) {
+        if (definitionDetails.type !== 'kanji' && AnkiUtil.fieldsObjectContainsMarker(fields, 'audio')) {
             const primaryCardAudio = this._displayAudio.getPrimaryCardAudio(definitionDetails.expression, definitionDetails.reading);
             let preferredAudioIndex = null;
             let sources2 = sources;
@@ -1504,11 +1505,11 @@ class Display extends EventDispatcher {
             audioDetails = {sources: sources2, preferredAudioIndex, customSourceUrl, customSourceType};
         }
 
-        const screenshotDetails = (this._ankiNoteBuilder.containsMarker(fields, 'screenshot') ? {tabId: this._contentOriginTabId, frameId: this._contentOriginFrameId, format, quality} : null);
+        const screenshotDetails = (AnkiUtil.fieldsObjectContainsMarker(fields, 'screenshot') ? {tabId: this._contentOriginTabId, frameId: this._contentOriginFrameId, format, quality} : null);
 
         const clipboardDetails = {
-            image: this._ankiNoteBuilder.containsMarker(fields, 'clipboard-image'),
-            text: this._ankiNoteBuilder.containsMarker(fields, 'clipboard-text')
+            image: AnkiUtil.fieldsObjectContainsMarker(fields, 'clipboard-image'),
+            text: AnkiUtil.fieldsObjectContainsMarker(fields, 'clipboard-text')
         };
 
         return await yomichan.api.injectAnkiNoteMedia(
diff --git a/ext/js/pages/settings/anki-controller.js b/ext/js/pages/settings/anki-controller.js
index 26cab68f..509e263c 100644
--- a/ext/js/pages/settings/anki-controller.js
+++ b/ext/js/pages/settings/anki-controller.js
@@ -17,7 +17,7 @@
 
 /* global
  * AnkiConnect
- * AnkiNoteBuilder
+ * AnkiUtil
  * ObjectPropertyAccessor
  * SelectorObserver
  */
@@ -26,7 +26,6 @@ class AnkiController {
     constructor(settingsController) {
         this._settingsController = settingsController;
         this._ankiConnect = new AnkiConnect();
-        this._ankiNoteBuilder = new AnkiNoteBuilder(false);
         this._selectorObserver = new SelectorObserver({
             selector: '.anki-card',
             ignoreSelector: null,
@@ -156,10 +155,6 @@ class AnkiController {
         return this._settingsController.permissionsUtil.getRequiredPermissionsForAnkiFieldValue(fieldValue);
     }
 
-    containsAnyMarker(field) {
-        return this._ankiNoteBuilder.containsAnyMarker(field);
-    }
-
     // Private
 
     async _onOptionsChanged({options: {anki}}) {
@@ -439,7 +434,7 @@ class AnkiCardController {
 
     _validateField(node, index) {
         let valid = (node.dataset.hasPermissions !== 'false');
-        if (valid && index === 0 && !this._ankiController.containsAnyMarker(node.value)) {
+        if (valid && index === 0 && !AnkiUtil.stringContainsAnyFieldMarker(node.value)) {
             valid = false;
         }
         node.dataset.invalid = `${!valid}`;
diff --git a/ext/js/pages/settings/anki-templates-controller.js b/ext/js/pages/settings/anki-templates-controller.js
index 8e3a1a70..710946be 100644
--- a/ext/js/pages/settings/anki-templates-controller.js
+++ b/ext/js/pages/settings/anki-templates-controller.js
@@ -32,7 +32,7 @@ class AnkiTemplatesController {
         this._renderFieldInput = null;
         this._renderResult = null;
         this._fieldTemplateResetModal = null;
-        this._ankiNoteBuilder = new AnkiNoteBuilder(true);
+        this._ankiNoteBuilder = new AnkiNoteBuilder();
     }
 
     async prepare() {
diff --git a/ext/permissions.html b/ext/permissions.html
index ded314a3..5bd6987f 100644
--- a/ext/permissions.html
+++ b/ext/permissions.html
@@ -167,6 +167,7 @@
 
 <script src="/js/comm/api.js"></script>
 <script src="/js/comm/cross-frame-api.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/data/permissions-util.js"></script>
 <script src="/js/dom/document-focus-controller.js"></script>
 <script src="/js/dom/html-template-collection.js"></script>
diff --git a/ext/popup.html b/ext/popup.html
index 88648809..60058b77 100644
--- a/ext/popup.html
+++ b/ext/popup.html
@@ -97,6 +97,7 @@
 <script src="/js/comm/cross-frame-api.js"></script>
 <script src="/js/comm/frame-endpoint.js"></script>
 <script src="/js/data/anki-note-builder.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/display/display.js"></script>
 <script src="/js/display/display-audio.js"></script>
 <script src="/js/display/display-generator.js"></script>
diff --git a/ext/search.html b/ext/search.html
index d1c28fc8..b5aa56f0 100644
--- a/ext/search.html
+++ b/ext/search.html
@@ -83,6 +83,7 @@
 <script src="/js/comm/clipboard-monitor.js"></script>
 <script src="/js/comm/cross-frame-api.js"></script>
 <script src="/js/data/anki-note-builder.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/display/display.js"></script>
 <script src="/js/display/display-audio.js"></script>
 <script src="/js/display/display-generator.js"></script>
diff --git a/ext/settings-old.html b/ext/settings-old.html
index 6d5bb6f7..be791bb2 100644
--- a/ext/settings-old.html
+++ b/ext/settings-old.html
@@ -1288,6 +1288,7 @@
         <script src="/js/comm/api.js"></script>
         <script src="/js/comm/cross-frame-api.js"></script>
         <script src="/js/data/anki-note-builder.js"></script>
+        <script src="/js/data/anki-util.js"></script>
         <script src="/js/data/database.js"></script>
         <script src="/js/data/json-schema.js"></script>
         <script src="/js/data/options-util.js"></script>
diff --git a/ext/settings.html b/ext/settings.html
index 2dcbc083..54ee7d6d 100644
--- a/ext/settings.html
+++ b/ext/settings.html
@@ -3198,6 +3198,7 @@
 <script src="/js/comm/api.js"></script>
 <script src="/js/comm/cross-frame-api.js"></script>
 <script src="/js/data/anki-note-builder.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/data/database.js"></script>
 <script src="/js/data/json-schema.js"></script>
 <script src="/js/data/options-util.js"></script>
diff --git a/ext/sw.js b/ext/sw.js
index 802f3ba3..89fb4d0f 100644
--- a/ext/sw.js
+++ b/ext/sw.js
@@ -28,6 +28,7 @@ self.importScripts(
     '/js/comm/clipboard-monitor.js',
     '/js/comm/clipboard-reader.js',
     '/js/comm/mecab.js',
+    '/js/data/anki-util.js',
     '/js/data/database.js',
     '/js/data/json-schema.js',
     '/js/data/options-util.js',
diff --git a/ext/welcome.html b/ext/welcome.html
index 22f6a681..5876ad4c 100644
--- a/ext/welcome.html
+++ b/ext/welcome.html
@@ -320,6 +320,7 @@
 
 <script src="/js/comm/api.js"></script>
 <script src="/js/comm/cross-frame-api.js"></script>
+<script src="/js/data/anki-util.js"></script>
 <script src="/js/data/database.js"></script>
 <script src="/js/data/json-schema.js"></script>
 <script src="/js/data/permissions-util.js"></script>