implement memoization for domain normalization

lib/utils.js

@@ -90,3 +90,24 @@ export const readFile = async (filePath, onLine) => {
     throw err;
   }
 };
+
+/**
+ * Memoizes a function
+ * @template T The argument type of the function.
+ * @template R The return type of the function.
+ * @param {(...fnArgs: T[]) => R} fn The function to be memoized.
+ */
+export const memoize = (fn) => {
+  const cache = new Map();
+
+  return (...args) => {
+    const key = args.join("-");
+
+    if (cache.has(key)) return cache.get(key);
+
+    const result = fn(...args);
+
+    cache.set(key, result);
+    return result;
+  };
+};