Fix numeric storage expires (#1099)

* Fix numeric storage expiries

* lint

* ===

* changeset

* always store as string

* extra test for string

.changeset/funny-jars-pump.md

@@ -0,0 +1,5 @@
+---
+'@guardian/libs': patch
+---
+
+Make Storage handle numeric expiry value

libs/@guardian/libs/src/storage/storage.test.ts

@@ -78,14 +78,30 @@ describe.each([
 		expect(implementation.get('thisDoesNotExist')).toBeNull();
 	});
 
-	it(`does not return an expired item`, () => {
+	it(`does not return an expired item with expiry as Date object`, () => {
 		implementation.set('iAmExpired', 'data', new Date('1901-01-01'));
 		expect(implementation.get('iAmExpired')).toBeNull();
 
 		// check it's been deleted too
 		expect(native.getItem('iAmExpired')).toBeNull();
 	});
 
+	it(`does not return an expired item with expiry as numeric value (millis since epoch)`, () => {
+		implementation.set('iAmExpired', 'data', new Date('1901-01-01').getTime());
+		expect(implementation.get('iAmExpired')).toBeNull();
+
+		// check it's been deleted too
+		expect(native.getItem('iAmExpired')).toBeNull();
+	});
+
+	it(`does not return an expired item with expiry as ISO date string`, () => {
+		implementation.set('iAmExpired', 'data', '1901-01-01T00:00:00.000Z');
+		expect(implementation.get('iAmExpired')).toBeNull();
+
+		// check it's been deleted too
+		expect(native.getItem('iAmExpired')).toBeNull();
+	});
+
 	it(`return null for a malformed item`, () => {
 		native.setItem('malformed', '[]');
 		expect(implementation.get('malformed')).toBeNull();

libs/@guardian/libs/src/storage/storage.ts

@@ -36,7 +36,10 @@ class StorageFactory {
 			const { value, expires } = data;
 
 			// is this item has passed its sell-by-date, remove it
-			if (isString(expires) && new Date() > new Date(expires)) {
+			if (
+				(isString(expires) || typeof expires === 'number') &&
+				new Date() > new Date(expires)
+			) {
 				this.remove(key);
 				return null;
 			}
@@ -59,7 +62,7 @@ class StorageFactory {
 			key,
 			JSON.stringify({
 				value,
-				expires,
+				expires: expires ? new Date(expires) : undefined,
 			}),
 		);
 	}