javascript - 时间戳倒计时变为负数

Question

我有一个倒计时时间戳的脚本。它工作正常，但问题是它一直小于 0 变为负值。我希望它停在零。

// $nowtime is a date in future
var startLive = new Date("<?php echo $nowtime; ?>");
var timestamp = startLive - Date.now();

timestamp /= 1000; // from ms to seconds

function component(x, v) {
  return Math.floor(x / v);
}

var $div = $('.time');

timer = setInterval(function() {

  timestamp--;

  var days = component(timestamp, 24 * 60 * 60),
    hours = component(timestamp, 60 * 60) % 24,
    minutes = component(timestamp, 60) % 60,
    seconds = component(timestamp, 1) % 60;

  $div.html(days + " days, " + hours + ":" + minutes + ":" + seconds);


}, 1000);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

Output looks like 1 Days, 6:10:30

问题是，如果它小于零，它仍然为负数。类似-3天，-3:-5:-5

如何在0处停止。

谢谢。

Answer 1

timer = setInterval(function() {

    /* if timestamp <= 0 return means skip rest of function */
    if(timestamp <= 0) {
        clearInterval(timer); 
        return;
    }

    timestamp--;

    var days    = component(timestamp, 24 * 60 * 60),
        hours   = component(timestamp,      60 * 60) % 24,
        minutes = component(timestamp,           60) % 60,
        seconds = component(timestamp,            1) % 60;

    $div.html(days + " days, " + hours + ":" + minutes + ":" + seconds);


}, 1000);