html 倒计时到分秒,js 实现时分秒倒计时

let timeId2 =null;

function countTime(lastTime) {

//获取当前时间

let date = new Date();

let now = date.getTime();

//设置截止时间

let endDate = new Date(lastTime);

let end = endDate.getTime();

//时间差

let leftTime = end-now;

//定义变量,h,m,s保存倒计时的时间

let h, m, s;

if (leftTime >= 0) {

h = Math.floor(leftTime / 1000 / 60 / 60);

m = Math.floor(leftTime / 1000 / 60 % 60);

s = Math.floor(leftTime / 1000 % 60);

if(h < 10){

document.getElementById("_h").innerHTML = "0";

document.getElementById("_h2").innerHTML = h;

}

else{

document.getElementById("_h").innerHTML = Math.floor(h / 10);

document.getElementById("_h2").innerHTML = h % 10;

}

if(m < 10){

document.getElementById("_m").innerHTML = "0";

document.getElementById("_m2").innerHTML = m;

}

else{

document.getElementById("_m").innerHTML = Math.floor(m / 10);

document.getElementById("_m2").innerHTML = m % 10;

}

if(s < 10){

document.getElementById("_s").innerHTML = "0";

document.getElementById("_s2").innerHTML = s;

}

else{

document.getElementById("_s").innerHTML = Math.floor(s / 10);

document.getElementById("_s2").innerHTML = s % 10;

}

} else {

document.getElementById("_h").innerHTML = "0";

document.getElementById("_h2").innerHTML = "0";

document.getElementById("_m").innerHTML = "0";

document.getElementById("_m2").innerHTML = "0";

document.getElementById("_s").innerHTML = "0";

document.getElementById("_s2").innerHTML = "0";

clearInterval(timeId2)

}

}

//注意时间会有误差所以是每1050毫秒掉一次

let lastTime = 200000 +(+new Date());

timeId2 = setInterval(()=>{

countTime(lastTime)

},1050)