如何网站运行后倒计时超时与编码器

我做了一个倒计时计时器，时间用完后我如何连接到网站?我使用CodeIgniter框架

这是我的脚本倒计时

<script>
var target_date = new Date('Sep, 18, 2015 15:02:00 GMT-0700').getTime();
var days, hours, minutes, seconds;
var countdown = document.getElementById('countdown');
setInterval(function () {
    var current_date = new Date().getTime();
    var seconds_left = (target_date - current_date) / 1000;
    days = parseInt(seconds_left / 86400);
    seconds_left = seconds_left % 86400;
    hours = parseInt(seconds_left / 3600);
    seconds_left = seconds_left % 3600;
    minutes = parseInt(seconds_left / 60);
    seconds = parseInt(seconds_left % 60);
    countdown.innerHTML = '<div id="days" class="timer_box"><h1>' + days +  '</h1> <p>Days</p></div> <div id="days" class="timer_box"><h1>' + hours + '</h1> <p>Hours</p></div> <div id="days" class="timer_box"><h1>'
    + minutes + '</h1> <p>Minutes</p></div> <div id="days" class="timer_box"><h1>' + seconds + '</h1> <p>Seconds</p></div>';  
}, 1000);
</script>