javascript [京东倒计时抢购]倒计时定时器#javascript

Posted 2021-05-04

var timeBox = document.getElementById('timeBox');
console.log(timeBox);

// 计算时间差
function computed() {
    var nowTime = new Date(),
        targetTime = new Date('2018/3/1 17:00:00');
    
    var spanTime = targetTime - nowTime; // 获取的结果是两个时间之间的毫秒差
    if (spanTime <= 0) {
        // 已经到达目标时间，此时可以提示开始考试
        timeBox.innerHTML  = '开始考试';
        window.clearInterval(timer);
        return;

    }


    var hour = Math.floor(spanTime / (1000 * 60 * 60));
    spanTime -= hour * 60 * 60 * 1000;  // 把小时占据的毫秒数去除，剩下的值中计算还有多少分钟

    var minute = Math.floor(spanTime / (1000 * 60));
    spanTime -= minute * 1000 * 60;

    var second = Math.floor(spanTime / 1000);
    // 不足10位补零
    hour <10 ? hour = '0' +hour :null;
    minute <10 ? minute = '0' +minute :null;
    second <10 ? second = '0' +second :null;
    timeBox.innerHTML = hour + ':' + minute + ':' + second;


}

computed();

var timer = window.setInterval(computed, 1000);