main
import { useEffect, useState } from 'react'
export function useCountdown(deadline: number) {
const [now, setNow] = useState(Date.now())
useEffect(() => {
setNow(Date.now())
if (deadline <= Date.now()) return
const timer = window.setInterval(() => setNow(Date.now()), 1000)
return () => clearInterval(timer)
}, [deadline])
return Math.max(0, Math.ceil((deadline - now) / 1000))
}