To Sther

gistfile1.txt

import React, { useState, useEffect } from 'react';

export function App(props) {
  const [time, setTime] = useState(25000);
  const [start, setStart] = useState(false);

  useEffect(() => {
    const timer = setInterval(() => {
      if (start && time > 0) {
        setTime(time - 1);
      }
    }, 1000);

    return () => clearInterval(timer);

  }, [start, time]);

  function startStopClock() {
    setStart(!start);
  }

  return (
    <div className='App'>
      <h1>{time.toString()}</h1>
      <button onClick={startStopClock}>{`${!start ? 'Start' : 'Stop'}`}</button>
    </div>
  );
}

export default App;