时间倒计时

从这简单的时间倒计功能开始，希望自己每天都能坚持学习

function showTime() {
    var curDate = new Date();
    var curYear = curDate.getFullYear();
    var cur_time = curDate.getTime();
    document.getElementById("t_year").innerHTML = curYear;
    var time_end = new Date(curYear + "/12/30 23:59:59");  // 设定今年结束时间
    var time_distance = time_end.getTime() - cur_time;
    if(time_distance > 0) {
        var int_day = Math.floor(time_distance/(24*60*60*1000));
        document.getElementById("t_day").innerHTML = int_day;
        time_distance = time_distance - int_day*24*60*60*1000;
        var int_hour = Math.floor(time_distance/(60*60*1000));
        if(int_hour < 10){
            int_hour = "0" + int_hour;
        }
        document.getElementById("t_hour").innerHTML = int_hour;

        time_distance = time_distance - int_hour*60*60*1000;
        var int_minute = Math.floor(time_distance/(60*1000));
        document.getElementById("t_minute").innerHTML = int_minute;

        time_distance = time_distance - int_minute*60*1000;
        var int_second = Math.floor(time_distance/1000);
        document.getElementById("t_second").innerHTML = int_second;
    }
}

window.setInterval(function(){showTime()}, 1000);