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diff --git a/ext/js/data/anki-util.js b/ext/js/data/anki-util.js
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+/*
+ * 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;