JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="app"></div>

Babel + JSX

function App() {
  const [ seconds, setSeconds ] = React.useState(60);
  const [ timerActive, setTimerActive ] = React.useState(false);

  React.useEffect(() => {
    if (seconds > 0 && timerActive) {
      setTimeout(setSeconds, 100, seconds - 1);
    } else {
      setTimerActive(false);
    }
  }, [ seconds, timerActive ]);

  return (
    <div>
      {seconds
        ? <React.Fragment>
            <button onClick={() => setTimerActive(!timerActive)}>
              {timerActive ? 'stop' : 'start'}
            </button>
            <div>{seconds}</div>
          </React.Fragment>
        : <button onClick={() => setSeconds(60)}>ещё раз</button>
      }
    </div>
  );
}

ReactDOM.render(<App />, document.getElementById('app'));