// RxJS v6+
import { of, from } from 'rxjs';
import { sequenceEqual, switchMap } from 'rxjs/operators';
​
const expectedSequence = from([4, 5, 6]);
​
of([1, 2, 3], [4, 5, 6], [7, 8, 9])
  .pipe(switchMap(arr => from(arr).pipe(sequenceEqual(expectedSequence))))
  .subscribe(console.log);
​
//output: false, true, false

// RxJS v6+
import { from, fromEvent } from 'rxjs';
import { sequenceEqual, map, bufferCount, mergeMap, tap } from 'rxjs/operators';
​
const expectedSequence = from(['q', 'w', 'e', 'r', 't', 'y']);
const setResult = text => (document.getElementById('result').innerText = text);
​
fromEvent(document, 'keydown')
  .pipe(
    map((e: KeyboardEvent) => e.key),
    tap(v => setResult(v)),
    bufferCount(6),
    mergeMap(keyDowns =>
      from(keyDowns).pipe(
        sequenceEqual(expectedSequence),
        tap(isItQwerty => setResult(isItQwerty ? 'WELL DONE!' : 'TYPE AGAIN!'))
      )
    )
  )
  .subscribe(e => console.log(`did you say qwerty? ${e}`));