adding in prepend

jaredwray · Oct 15, 2024 · 6f58fcf · 6f58fcf
1 parent 627f6eb
commit 6f58fcf
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Showing 2 changed files with 54 additions and 2 deletions.
diff --git a/src/eventified.ts b/src/eventified.ts
@@ -44,11 +44,21 @@ export class Eventified implements IEventEmitter {
 	}
 
 	prependListener(eventName: string | symbol, listener: EventListener): IEventEmitter {
-		throw new Error('Method not implemented.');
+		const listeners = this._eventListeners.get(eventName) ?? [];
+		listeners.unshift(listener);
+		this._eventListeners.set(eventName, listeners);
+		return this;
 	}
 
 	prependOnceListener(eventName: string | symbol, listener: EventListener): IEventEmitter {
-		throw new Error('Method not implemented.');
+		const onceListener: EventListener = (...arguments_: any[]) => {
+			this.off(eventName as string, onceListener);
+			// eslint-disable-next-line @typescript-eslint/no-unsafe-argument
+			listener(...arguments_);
+		};
+
+		this.prependListener(eventName as string, onceListener);
+		return this;
 	}
 
 	public maxListeners(): number {

diff --git a/test/eventified.test.ts b/test/eventified.test.ts
@@ -162,6 +162,11 @@ describe('Eventified', () => {
 		t.expect(emitter.listenerCount('test-event')).toBe(2);
 	});
 
+	test('no listener count', t => {
+		const emitter = new Eventified();
+		t.expect(emitter.listenerCount('test-event')).toBe(0);
+	});
+
 	test('get event names', t => {
 		const emitter = new Eventified();
 		const listener = () => {};
@@ -186,4 +191,41 @@ describe('Eventified', () => {
 		t.expect(emitter.rawListeners('test-event1')).toEqual([listener]);
 		t.expect(emitter.rawListeners().length).toEqual(4);
 	});
+
+	test('get raw listeners when no listeners', t => {
+		const emitter = new Eventified();
+		t.expect(emitter.rawListeners('test-event')).toEqual([]);
+	});
+
+	test('prepend listener', t => {
+		const emitter = new Eventified();
+		const listener = () => {};
+
+		emitter.on('test-event', listener);
+		emitter.prependListener('test-event', () => {});
+
+		t.expect(emitter.rawListeners('test-event').length).toBe(2);
+		t.expect(emitter.rawListeners('test-event')[0]).not.toBe(listener);
+	});
+
+	test('prepend with no listenters', t => {
+		const emitter = new Eventified();
+		emitter.prependListener('test-event', () => {});
+		t.expect(emitter.rawListeners('test-event').length).toBe(1);
+	});
+
+	test('prepend once listener', t => {
+		const emitter = new Eventified();
+		const listener = () => {};
+
+		emitter.on('test-event', listener);
+		emitter.prependOnceListener('test-event', () => {});
+
+		t.expect(emitter.rawListeners('test-event').length).toBe(2);
+		t.expect(emitter.rawListeners('test-event')[0]).not.toBe(listener);
+
+		emitter.emit('test-event');
+
+		t.expect(emitter.rawListeners('test-event').length).toBe(1);
+	});
 });