Konami RxJS 7

konami.ts

const table: {[key: string]: number} = {
    ArrowUp: 38,
    ArrowDown: 40,
    ArrowLeft: 37,
    ArrowRight: 39,
    KeyB: 66,
    // Azerty compat
    KeyQ: 65,
    KeyA: 65,
};
 
const knownSequence = from([38, 38, 40, 40, 37, 39, 37, 39, 66, 65]);
 
const x$ = fromEvent<KeyboardEvent>(document, 'keyup').pipe(
    map((e) => table[e.code] ? table[e.code] : -1),
    skipWhile((k) => k !== 38),
    bufferCount(10, 1),
    mergeMap((x) => {
        return from(x).pipe(sequenceEqual(knownSequence));
    }),
    filter((sequenceEqual) => sequenceEqual),
    switchMap((_) => of('konami'))
);
 
await firstValueFrom(x$);
// Do x thing