Update map

Live Editor

function Clock(props) { const [date, setDate] = useState(new Date()); useEffect(() => { const timerID = setInterval(() => tick(), 1000); return function cleanup() { clearInterval(timerID); }; }); function tick() { setDate(new Date()); } return ( <div> <h2>It is {date.toLocaleTimeString()}.</h2> </div> ); }

function Clock(props) {
  const [date, setDate] = useState(new Date());
  useEffect(() => {
    const timerID = setInterval(() => tick(), 1000);

    return function cleanup() {
      clearInterval(timerID);
    };
  });

  function tick() {
    setDate(new Date());
  }

  return (
    <div>
      <h2>It is {date.toLocaleTimeString()}.</h2>
    </div>
  );
}

Result

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