SOURCE

const el = document.getElementById('text')
const target = new Date('2023-05-23 22:59:59')
const intervalId = null

function makeCountdown() {
    let currTime = new Date().getTime()
    let leftTime = target.getTime() - currTime

    if (leftTime <= 0) clearInterval(intervalId)

    let d = Math.floor(leftTime / (1000 * 60 * 60 * 24))
    let h = Math.floor((leftTime / (1000 * 60 * 60)) % 24)
    let m = Math.floor((leftTime / (1000 * 60)) % 60);
    let s = Math.floor((leftTime / 1000) % 60);

    console.log('days left: ', d, ' hours left: ', h, 'minuts left: ', m, 'seconds left: ', s)
    el.innerText = `${d}天${h}小时${m}分钟${s}秒`
}

function onLoad() {
    intervalId = setInterval(makeCountdown, 1000)
}

onLoad()

距离结束还有：<div id='text'>00:00:00</div>