Use custom cache expiration logic

Fixes #92

index.ts

@@ -1,9 +1,9 @@
 import mimicFunction from 'mimic-function';
-import mapAgeCleaner from 'map-age-cleaner';
 
-type AnyFunction = (...arguments_: readonly any[]) => any;
+type AnyFunction = (...arguments_: readonly any[]) => unknown;
 
 const cacheStore = new WeakMap<AnyFunction, CacheStorage<any, any>>();
+const cacheTimerStore = new WeakMap<AnyFunction, Set<number>>();
 
 type CacheStorageContent<ValueType> = {
 	data: ValueType;
@@ -104,8 +104,8 @@ export default function mem<
 		maxAge,
 	}: Options<FunctionToMemoize, CacheKeyType> = {},
 ): FunctionToMemoize {
-	if (typeof maxAge === 'number') {
-		mapAgeCleaner(cache as unknown as Map<CacheKeyType, ReturnType<FunctionToMemoize>>);
+	if (typeof maxAge === 'number' && maxAge <= 0) {
+		return fn;
 	}
 
 	const memoized = function (this: any, ...arguments_: Parameters<FunctionToMemoize>): ReturnType<FunctionToMemoize> {
@@ -123,6 +123,18 @@ export default function mem<
 			maxAge: maxAge ? Date.now() + maxAge : Number.POSITIVE_INFINITY,
 		});
 
+		if (typeof maxAge === 'number' && maxAge !== Number.POSITIVE_INFINITY) {
+			const timer = setTimeout(() => {
+				cache.delete(key);
+			}, maxAge);
+
+			timer.unref?.();
+
+			const timers = cacheTimerStore.get(fn) ?? new Set();
+			timers.add(timer as any); // eslint-disable-line @typescript-eslint/no-unsafe-argument
+			cacheTimerStore.set(fn, timers);
+		}
+
 		return result;
 	} as FunctionToMemoize;
 
@@ -198,7 +210,7 @@ export function memDecorator<
 /**
 Clear all cached data of a memoized function.
 
-@param fn - Memoized function.
+@param fn - The memoized function.
 */
 export function memClear(fn: AnyFunction): void {
 	const cache = cacheStore.get(fn);
@@ -211,4 +223,8 @@ export function memClear(fn: AnyFunction): void {
 	}
 
 	cache.clear();
+
+	for (const timer of cacheTimerStore.get(fn) ?? []) {
+		clearTimeout(timer);
+	}
 }

package.json

@@ -41,7 +41,6 @@
 		"promise"
 	],
 	"dependencies": {
-		"map-age-cleaner": "^0.2.0",
 		"mimic-function": "^5.0.0"
 	},
 	"devDependencies": {

readme.md

@@ -244,7 +244,7 @@ Clear all cached data of a memoized function.
 
 Type: `Function`
 
-Memoized function.
+The memoized function.
 
 ## Tips
 

test.ts

@@ -240,3 +240,79 @@ test('memClear() throws when called on an unclearable cache', t => {
 		instanceOf: TypeError,
 	});
 });
+
+test('maxAge - cache item expires after specified duration', async t => {
+	let i = 0;
+	const fixture = () => i++;
+	const memoized = mem(fixture, {maxAge: 100});
+
+	t.is(memoized(), 0); // Initial call, cached
+	t.is(memoized(), 0); // Subsequent call, still cached
+	await delay(150); // Wait for longer than maxAge
+	t.is(memoized(), 1); // Cache expired, should compute again
+});
+
+test('maxAge - cache expiration timing is accurate', async t => {
+	let i = 0;
+	const fixture = () => i++;
+	const memoized = mem(fixture, {maxAge: 100});
+
+	t.is(memoized(), 0);
+	await delay(90); // Wait for slightly less than maxAge
+	t.is(memoized(), 0); // Should still be cached
+	await delay(20); // Total delay now exceeds maxAge
+	t.is(memoized(), 1); // Should recompute as cache has expired
+});
+
+test('maxAge - expired items are not present in cache', async t => {
+	let i = 0;
+	const fixture = () => i++;
+	const cache = new Map();
+	const memoized = mem(fixture, {maxAge: 100, cache});
+
+	memoized(); // Call to cache the result
+	await delay(150); // Wait for cache to expire
+	memoized(); // Recompute and recache
+	t.is(cache.size, 1); // Only one item should be in the cache
+});
+
+test('maxAge - complex arguments and cache expiration', async t => {
+	let i = 0;
+	const fixture = object => i++;
+	const memoized = mem(fixture, {maxAge: 100, cacheKey: JSON.stringify});
+
+	const arg = {key: 'value'};
+	t.is(memoized(arg), 0);
+	await delay(150);
+	t.is(memoized(arg), 1); // Argument is the same, but should recompute due to expiration
+});
+
+test('maxAge - concurrent calls return cached value', async t => {
+	let i = 0;
+	const fixture = () => i++;
+	const memoized = mem(fixture, {maxAge: 100});
+
+	t.is(memoized(), 0);
+	await delay(50); // Delay less than maxAge
+	t.is(memoized(), 0); // Should return cached value
+});
+
+test('maxAge - different arguments have separate expirations', async t => {
+	let i = 0;
+	const fixture = x => i++;
+	const memoized = mem(fixture, {maxAge: 100});
+
+	t.is(memoized('a'), 0);
+	await delay(150); // Expire the cache for 'a'
+	t.is(memoized('b'), 1); // 'b' should be a separate cache entry
+	t.is(memoized('a'), 2); // 'a' should be recomputed
+});
+
+test('maxAge - zero maxAge means no caching', t => {
+	let i = 0;
+	const fixture = () => i++;
+	const memoized = mem(fixture, {maxAge: 0});
+
+	t.is(memoized(), 0);
+	t.is(memoized(), 1); // No caching, should increment
+});