JavaScript倒计时实现

/**
 * 倒计时函数
 * @param {String}} endTime 终止时间戳
 */
const countDown = (endTime, callback) => {
    const end = endTime,
        now = new Date().getTime();
    let differ = end - now,
        hours, minutes, seconds;
    if (differ >= 0) {
        hours = Math.floor(differ / 1000 / 60 / 60 % 24);
        minutes = Math.floor(differ / 1000 / 60 % 60);
        seconds = Math.floor(differ / 1000 % 60);
    }
    callback({
        h: check(hours),
        m: check(minutes),
        s: check(seconds)
    });
    setTimeout(() => {
        countDown(end, callback);
    }, 1000);
};

/**
 * 时间前加零
 * @param {Number} time
 */
const check = time => {
    if (time < 10) {
        time = '0' + time;
    }
    return time.toString();
};

export default countDown;

countDown(new Date('2018/9/5 10:00:00'), function(timeObj) { // 调用
      console.log(timeObj.h, timeObj.m, timeObj.s)
});