useCountdown

Medium

Prompt

Build a React hook called useCountdown that runs a countdown from a starting number of seconds down to zero.

const { isRunning, start, stop, seconds } =
  useCountdown(totalTime);

What the hook returns:

seconds: the current number of seconds left. Starts at totalTime.
isRunning: true while the countdown is active, false otherwise.
start: a function that begins the countdown.
stop: a function that ends the countdown and puts seconds back to totalTime.

How the countdown behaves:

At the start, the countdown is idle: seconds is totalTime and isRunning is false.
After calling start(), seconds drops by 1 every second until it reaches zero.
If stop() is called at any point, the countdown ends right away and seconds returns to totalTime.
When the countdown runs all the way to zero on its own, the hook behaves as if stop() was called: isRunning becomes false and seconds is reset to totalTime.

What the demo page should show: