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How to Create a Countdown Timer with React?

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Sometimes, we want to create a countdown timer with React.

In this article, we’ll look at how to create a countdown timer with React.

Create a Countdown Timer with React

We can create a countdown timer by creating a timer component that updates the remaining time regularly.

To do this, we write:

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

const Timer = (props) => {
  const { initialMinute = 0, initialSeconds = 0 } = props;
  const [minutes, setMinutes] = useState(initialMinute);
  const [seconds, setSeconds] = useState(initialSeconds);
  useEffect(() => {
    const myInterval = setInterval(() => {
      if (seconds > 0) {
        setSeconds(seconds - 1);
      }
      if (seconds === 0) {
        if (minutes === 0) {
          clearInterval(myInterval);
        } else {
          setMinutes(minutes - 1);
          setSeconds(59);
        }
      }
    }, 1000);
    return () => {
      clearInterval(myInterval);
    };
  });

  return (
    <div>
      {minutes === 0 && seconds === 0 ? null : (
        <h1>
          {minutes}:{seconds < 10 ? `0${seconds}` : seconds}
        </h1>
      )}
    </div>
  );
};

export default function App() {
  return (
    <>
      <Timer initialMinute={5} initialSeconds={0} />
    </>
  );
}

We create the Timer component that takes the initialMinute and initialSeconds props that sets the initial time.

Then we use the useState prop to create the minutes and seconds state.

Next, we call the useEffect hook with a callback that creates a timer with setInterval .

The timer runs every second.

The setInterval callback checks if the seconds is bigger than 0 and calls setSeconds to decrease the seconds.

If seconds is 0 and minutes is 0, then we call clearInteraval to stop the timer.

Otherwise, we call setMinutes to minutes — 1 and call setSeconds to 59 decrements the minute.

Then we return a callback that calls clearInterval to clear the timer.

Below that, we render the minutes and seconds onto the screen.

If seconds is less than 10 then we add a 0 in front of it.

Conclusion

We can create a countdown timer by creating a timer component that updates the remaining time regularly.

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