js实现日期天数、时分秒的倒计时

js实现天数倒计时

在用js实现倒计时的时候，可以先算出截止日期和今天之间相差的毫秒数，然后进行相应的比例进行day、 month 、hour、minute、second的计算，便可以准确的计算出相差的时间。

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倒计时格式为：纯天数倒计时

function countDown(year, month, day, hours) {
    
    
    let now = new Date();
    let endDate = new Date(year, month - 1, day, hours);
    let leftTime = endDate.getTime() - now.getTime(); //计算剩余的毫秒数
    if (leftTime <= 0) {
    
    
        leftTime = 0;
    }
    let leftsecond = parseInt(leftTime / 1000); //计算剩余的秒数
    let countDay = Math.floor(leftsecond / (60 * 60 * 24));
    return countDay;
}

countDown(2023, 1, 21, 0);

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倒计时格式为：天数+小时+分钟+秒

function countDown(year, month, day, hours) {
    
    
    let now = new Date();
    let endDate = new Date(year, month - 1, day, hours);
    let leftTime = endDate.getTime() - now.getTime(); //计算剩余的毫秒数
    if (leftTime <= 0) {
    
    
        leftTime = 0;
    }
    let leftsecond = parseInt(leftTime / 1000); //计算剩余的秒数
    day = Math.floor(leftsecond / (60 * 60 * 24));
    let hour = Math.floor((leftsecond - day * 24 * 60 * 60) / 3600);
    let minute = Math.floor((leftsecond - day * 24 * 60 * 60 - hour * 3600) / 60);
    let second = Math.floor(leftTime / 1000 % 60, 10);
    return `${
      
      day}天${
      
      hour}小时${
      
      minute}分钟${
      
      second}秒`;
}

countDown(2023, 1, 21, 0);