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let osoby=["Jan Nowak","Kazimierz Zyga","Stefan Koc","Ewa Mocek","Mariusz Abramski"]
/* Array.isArray() to metoda, która zwraca wartość logiczną true
jeśli obiekt jest tablicą, a wartość false jeśli nie jest.
Do takiego sprawdzenia nie używamy - typeof,
które dla obiektu i tablicy zwróci: "object". */
(Array.isArray(osoby)) ? body.innerHTML ="osoby to tablica" : body.innerHTML ="osoby to nie tablica";