Use Setinterval In React

I'm trying to use setInterval in React but stuck on something I don't properly understand. The code is: const Countdown = () => { const [countdownSecond, setCountdownSecond]

Solution 1:

You can do:

const Countdown = () => {
   const [countdownSecond, setCountdownSecond] = React.useState(0);
   const [start, setStart] = React.useState(false);

   React.useEffect(()=>{
       const interval = null
       if (start) {
           interval = setInterval(()=>{
               setCountdownSecond(countdownSecond + 1);
           }, 1000);
       }
       return ()=>{if (interval !== null) clearInterval(interval)};
   },[start]);

   function x(e) {
      e.preventDefault();
      console.log(countdownSecond);
      setStart(!start);
   }

  return (
    <>
      <button onClick={(e) => x(e)}>{start?"Stop":"Start"}</button>
      <p>Countdown:&nbsp;{countdownSecond}</p>
    </>
  );
}