useTimer Custom Hook

useTimer

import { useEffect, useState } from 'react';

//when I use this Hook, I will give it the timer target time in minutes

const useTimer = ({targetTimeMins}) => {
 
 //minutes are converted to milliseconds
 const targetTimeMS = targetTimeMins * 60 * 1000


 const [timer, setTimer] = useState(targetTimeMS)


 useEffect(() => {
   let timeRemaining = targetTimeMS
   
   //every 1 second, update the time remaining to be one second less
   const interval = setInterval(() => {
     setTimer(timeRemaining)
     timeRemaining -= 1000
   }, 1000)


   return () => clearInterval(interval)
 }, [targetTimeMS])

 //send back the time remaining (ms) to the getReturnedValues function
 return getReturnedValues(timer)
}


const getReturnedValues = (timer) => {

 //convert the time remaining to minutes and seconds
 const minutes = Math.floor(timer / (1000 * 60))
 const seconds = Math.floor((timer % (1000 * 60)) / 1000)

 //return the minutes and seconds remaining
 return [minutes, seconds]
}


export { useTimer }