方案一：
function countDown(time) {var nowTime = +new Date();//返回的是当前时间的总毫秒数var inputTime = + new Date(time); //返回的是用户输入时间总的毫秒数var times = (inputTime - nowTime) / 1000; //times是剩余时间的总数var d = parseInt(times / 60 / 60 / 24); //计算天数var h = parseInt(times / 60 / 60 % 24);//计算小时var m = parseInt(times / 60 % 60);//计算分数var s = parseInt(times % 60);//计算秒数return d + '天' + h + '时' + m + '分' + s + '秒';}document.write(countDown('3021-10-27 18:00:00'));var date = new Date();document.write('<br>' + date);
方案二：
<div><span class="hour">0</span><span class="minute">0</span><span class="second">0</span></div>
div{width:300px;height:100px;margin:100px auto;box-sizing: border-box;display: flex;flex-direction: ;}span{width: 80px;height:100px;line-height:100px;text-align: center;background-color: darkslategrey;color: #fff;font-size: 20px;box-sizing: border-box;}
// 获取元素var hour = document.querySelector('.hour'); //小时的盒子var minute = document.querySelector('.minute'); //分钟var second = document.querySelector('.second'); //秒数var inputTime = + new Date('2021-10-28 18:00:00'); //返回的是用户输入时间总的毫秒数// 开启定时器countDown();setInterval(countDown,1000);function countDown(time) {var nowTime = +new Date();//返回的是当前时间的总毫秒数var times = (inputTime - nowTime) / 1000; //times是剩余时间的总数// var d = parseInt(times / 60 / 60 / 24); //计算天数var h = parseInt(times / 60 / 60 % 24);//计算小时h = h < 10 ? '0' + h : h;hour.innerHTML = h; //把剩余时间给小时的盒子var m = parseInt(times / 60 % 60);//计算分数m = m < 10 ? '0' + m : m;minute.innerHTML = m; //把剩余时间给分钟的盒子var s = parseInt(times % 60);//计算秒数s = s < 10 ? '0' + s : s;second.innerHTML = s; //把剩余时间给秒数的盒子// return d + '天' + h + '时' + m + '分' + s + '秒';}// document.write(countDown('2021-10-27 18:00:00'));// var date = new Date();// document.write('<br>' + date);
