init

src/emitter.ts

@@ -0,0 +1,28 @@
+export type Listener<T> = (event: T) => any;
+
+export class Emitter<T> {
+	private listeners: {[key: string]: Listener<T>} = {};
+
+	constructor() { }
+
+	emit(e: T) {
+		Object.values(this.listeners).forEach(l => l(e));
+	}
+
+	listen(fn: Listener<T>): () => {};
+	listen(key: string, fn: Listener<T>): () => {};
+	listen(keyOrFn: string | Listener<T>, fn?: Listener<T>): () => {} {
+		const func: any = fn ? fn : keyOrFn;
+		const key: string = typeof keyOrFn == 'string' ? keyOrFn :
+			`_${Object.keys(this.listeners).length.toString()}`;
+		this.listeners[<any>key] = func;
+		return () => delete this.listeners[<any>key];
+	}
+
+	once(fn: Listener<T>) {
+		const stop = this.listen(e => {
+			fn(e);
+			stop();
+		});
+	}
+}