refactor(client): allow receiving metadata

see #7

src/client.ts

@@ -7,12 +7,14 @@ import { Node, nodeify, traverseNode, unwrap } from './node';
 
 type Unsubscriber = () => void;
 
+type Meta = { [namespace: string]: any };
+
 export type ChainReference = {
 	get: (path: string) => ChainReference;
 	each: (callback: (ref: ChainReference, key: string) => void) => Unsubscriber;
 	set: (value: any) => ChainReference;
-	on: (callback: (data: any) => void) => Unsubscriber;
-	once: (callback: (data: any) => void) => void;
+	on: (callback: (data: any, meta: Meta) => void) => Unsubscriber;
+	once: (callback: (data: any, meta: Meta) => void) => void;
 };
 
 type UpdateListener = {
@@ -189,7 +191,7 @@ export function SocketDBClient({
 			},
 			on(callback) {
 				const listener = (data: Node) => {
-					callback(unwrap(data));
+					callback(unwrap(data), data.meta);
 				};
 				subscribe(path, listener);
 				return () => {
@@ -201,7 +203,7 @@ export function SocketDBClient({
 					// maybe should use subscribe {once: true} ?
 					// and not send "unsubscribe" back
 					unsubscribe(path, listener);
-					callback(unwrap(data));
+					callback(unwrap(data), data.meta);
 				});
 			},
 		};

test/client.test.ts

@@ -271,6 +271,33 @@ test('received data should not be passed as reference', (done) => {
 	client.get('data').set(testData);
 });
 
+test('also receives metadata', (done) => {
+	const metaExample = { owner: 'Thomas' };
+	const { addListener, removeListener, notify } = createEventBroker();
+	const socketClient: SocketClient = {
+		onConnect() {},
+		onDisconnect() {},
+		off: removeListener,
+		on: addListener,
+		send(event) {
+			if (event === 'subscribe') {
+				notify('players/1', {
+					data: { meta: metaExample, value: 'Thomas' },
+				});
+			}
+		},
+	};
+	const client = SocketDBClient({ socketClient });
+
+	client
+		.get('players')
+		.get('1')
+		.on((_, meta) => {
+			expect(meta).toEqual(metaExample);
+			done();
+		});
+});
+
 test('on/once always receives data on first call', (done) => {
 	const { addListener, removeListener, notify } = createEventBroker();
 	const socketClient: SocketClient = {
@@ -286,14 +313,15 @@ test('on/once always receives data on first call', (done) => {
 					.get('1')
 					.on(() => {
 						updateCount++;
+						expect(updateCount).toBe(2);
 						done();
 					});
 			}
 		},
 	};
 	const client = SocketDBClient({ socketClient });
 
-	let updateCount = 1;
+	let updateCount = 0;
 	client
 		.get('players')
 		.get('1')