1 files changed, 26 insertions, 0 deletions
diff --git a/ext/bg/js/util.js b/ext/bg/js/util.js
index f44582eb..9a3a2a3e 100644
--- a/ext/bg/js/util.js
+++ b/ext/bg/js/util.js
@@ -26,6 +26,32 @@ function utilIsolate(data) {
     return JSON.parse(JSON.stringify(data));
 }
 
+function utilSetEqual(setA, setB) {
+    if (setA.size !== setB.size) {
+        return false;
+    }
+
+    for (const value of setA) {
+        if (!setB.has(value)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+function utilSetIntersection(setA, setB) {
+    return new Set(
+        [...setA].filter(value => setB.has(value))
+    );
+}
+
+function utilSetDifference(setA, setB) {
+    return new Set(
+        [...setA].filter(value => !setB.has(value))
+    );
+}
+
 function utilBackend() {
     return chrome.extension.getBackgroundPage().yomichan_backend;
 }