当剩余时间少于24小时时，显示倒计时。

Question

我试图让我的倒计时时钟只在剩下不到24小时的时候出现.我没有写原始代码。我想应该是...

if (distance < end + ???) {

但我不知道该加什么？下面是完整的代码...

var end = new Date('05/03/2020 20:00 UTC+1');  
var _second = 1000;
var _minute = _second * 60;
var _hour = _minute * 60;
var _day = _hour * 24;
var timer;

function showRemaining() {
    var now = new Date();
    var distance = end - now;

    // When countdown over show finished
    if (distance < 0) {

        clearInterval(timer);
        document.getElementById('countdown').innerHTML =
        "Finished!";

        return;
    }

    var days = Math.floor(distance / _day);
    var hours = Math.floor((distance % _day) / _hour);
    var minutes = Math.floor((distance % _hour) / _minute);
    var seconds = Math.floor((distance % _minute) / _second);

// Only show countdown is less than 24 hours remains
    if (distance < end + ???) {
         // document.getElementById('countdown').innerHTML = days + ':';
          document.getElementById('countdown').innerHTML = hours + ' : ';
          document.getElementById('countdown').innerHTML += minutes + ' : ';
          document.getElementById('countdown').innerHTML += seconds + '';
      }
  }

timer = setInterval(showRemaining, 1000);     

https:/jsfiddle.netyvb4dahn3

Answer 1

如果你把你的条件改成这样就可以了 if (distance < 86400000) {. 这个数字是24小时，单位是毫秒。

var end = new Date('05/03/2020 10:00 UTC+1');  
var _second = 1000;
var _minute = _second * 60;
var _hour = _minute * 60;
var _day = _hour * 24;
var timer;

function showRemaining() {
    var now = new Date();
    var distance = end - now;

    // When countdown over show finished
    if (distance < 0) {

        clearInterval(timer);
        document.getElementById('countdown').innerHTML =
        "Finished!";

        return;
    }
    
    var days = Math.floor(distance / _day);
    var hours = Math.floor((distance % _day) / _hour);
    var minutes = Math.floor((distance % _hour) / _minute);
    var seconds = Math.floor((distance % _minute) / _second);

// Only show countdown is less than 24 hours remains
	if (distance < 86400000) {
         // document.getElementById('countdown').innerHTML = days + ':';
          document.getElementById('countdown').innerHTML = hours + ' : ';
          document.getElementById('countdown').innerHTML += minutes + ' : ';
          document.getElementById('countdown').innerHTML += seconds + '';
      }
  }

timer = setInterval(showRemaining, 1000);    

<div id="countdown"></div>

更多关于js日期和格式的信息。https:/developer.mozilla.orgen-USdocsWebJavaScriptReferenceGlobal_ObjectsDate。

希望对你有所帮助:)

Answer 2

你可以用这个来计算时间差。

var oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
var firstDate = new Date('05/03/2020 20:00 UTC+1');
var secondDate = new Date();

var diffDays = Math.round(Math.abs((firstDate - secondDate) / oneDay));

这将给你1的结果，所以你需要做的是：

if (diffDays < 2 && diffDays > 0)

只有在剩下一天的时候才会开始。

var end = new Date('05/03/2020 20:00 UTC+1');  
var _second = 1000;
var _minute = _second * 60;
var _hour = _minute * 60;
var _day = _hour * 24;
var timer;

function showRemaining() {
    var now = new Date();
    var distance = end - now;
    
    // When countdown over show finished
    if (distance < 0) {

        clearInterval(timer);
        document.getElementById('countdown').innerHTML =
        "Finished!";

        return;
    }
    
    var days = Math.floor(distance / _day);
    var hours = Math.floor((distance % _day) / _hour);
    var minutes = Math.floor((distance % _hour) / _minute);
    var seconds = Math.floor((distance % _minute) / _second);

// Only show countdown is less than 24 hours remains


var oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
var firstDate = new Date('05/03/2020 20:00 UTC+1');
var secondDate = new Date();

var diffDays = Math.round(Math.abs((firstDate - secondDate) / oneDay));
 
	if (diffDays < 2 && diffDays > 0) {
         // document.getElementById('countdown').innerHTML = days + ':';
          document.getElementById('countdown').innerHTML = hours + ' : ';
          document.getElementById('countdown').innerHTML += minutes + ' : ';
          document.getElementById('countdown').innerHTML += seconds + '';
      }
  }

timer = setInterval(showRemaining, 1000);

<div id="countdown"></div>