倒计时

function countdown() {
    const deadline = new Date('2022-06-18 00:00:00)
    const now = new Date()
    const time = deadline - now
    if (time < 0) return
    let day = Math.floor(time / 1000 / 60 / 60 / 24)
    let hour = Math.floor(time / 1000 / 60 / 60 % 24)
    let minute = Math.floor(time / 1000 / 60 % 60)
    let second = Math.floor(time / 1000 % 60)
    
    setTimeout(countdowm, 1000)
}