jQuery 一个简单的 JavaScript 倒数计时器的代码？

Code for a simple JavaScript countdown timer?

提问by Mike

I want to use a simple countdown timer starting at 30 seconds from when the function is run and ending at 0. No milliseconds. How can it be coded?

我想使用一个简单的倒数计时器，从函数运行时的 30 秒开始到 0 结束。没有毫秒。如何编码？

回答by Click Upvote

var count=30;

var counter=setInterval(timer, 1000); //1000 will  run it every 1 second

function timer()
{
  count=count-1;
  if (count <= 0)
  {
     clearInterval(counter);
     //counter ended, do something here
     return;
  }

  //Do code for showing the number of seconds here
}

To make the code for the timer appear in a paragraph (or anywhere else on the page), just put the line:

要使计时器的代码出现在段落（或页面上的任何其他地方）中，只需输入以下行：

<span id="timer"></span>

where you want the seconds to appear. Then insert the following line in your timer()function, so it looks like this:

您希望秒数出现的位置。然后在您的timer()函数中插入以下行，如下所示：

function timer()
{
  count=count-1;
  if (count <= 0)
  {
     clearInterval(counter);
     return;
  }

 document.getElementById("timer").innerHTML=count + " secs"; // watch for spelling
}

回答by CMS

I wrote this script some time ago:

我前段时间写了这个脚本：

Usage:

用法：

var myCounter = new Countdown({  
    seconds:5,  // number of seconds to count down
    onUpdateStatus: function(sec){console.log(sec);}, // callback for each second
    onCounterEnd: function(){ alert('counter ended!');} // final action
});

myCounter.start();

---

---

function Countdown(options) {
  var timer,
  instance = this,
  seconds = options.seconds || 10,
  updateStatus = options.onUpdateStatus || function () {},
  counterEnd = options.onCounterEnd || function () {};

  function decrementCounter() {
    updateStatus(seconds);
    if (seconds === 0) {
      counterEnd();
      instance.stop();
    }
    seconds--;
  }

  this.start = function () {
    clearInterval(timer);
    timer = 0;
    seconds = options.seconds;
    timer = setInterval(decrementCounter, 1000);
  };

  this.stop = function () {
    clearInterval(timer);
  };
}

回答by Niet the Dark Absol

So far the answers seem to rely on code being run instantly. If you set a timer for 1000ms, it will actually be around 1008 instead.

到目前为止，答案似乎依赖于立即运行的代码。如果您将计时器设置为 1000 毫秒，则实际上会在 1008 左右。

Here is how you should do it:

以下是您应该如何操作：

function timer(time,update,complete) {
    var start = new Date().getTime();
    var interval = setInterval(function() {
        var now = time-(new Date().getTime()-start);
        if( now <= 0) {
            clearInterval(interval);
            complete();
        }
        else update(Math.floor(now/1000));
    },100); // the smaller this number, the more accurate the timer will be
}

To use, call:

要使用，请致电：

timer(
    5000, // milliseconds
    function(timeleft) { // called every step to update the visible countdown
        document.getElementById('timer').innerHTML = timeleft+" second(s)";
    },
    function() { // what to do after
        alert("Timer complete!");
    }
);

回答by Layton Everson

Here is another one if anyone needs one for minutes and seconds:

如果有人在几分钟和几秒钟内需要一个，这是另一个：

    var mins = 10;  //Set the number of minutes you need
    var secs = mins * 60;
    var currentSeconds = 0;
    var currentMinutes = 0;
    /* 
     * The following line has been commented out due to a suggestion left in the comments. The line below it has not been tested. 
     * setTimeout('Decrement()',1000);
     */
    setTimeout(Decrement,1000); 

    function Decrement() {
        currentMinutes = Math.floor(secs / 60);
        currentSeconds = secs % 60;
        if(currentSeconds <= 9) currentSeconds = "0" + currentSeconds;
        secs--;
        document.getElementById("timerText").innerHTML = currentMinutes + ":" + currentSeconds; //Set the element id you need the time put into.
        if(secs !== -1) setTimeout('Decrement()',1000);
    }

回答by Rohit Sharma

Just modified @ClickUpvote's answer:

刚刚修改了@ClickUpvote 的回答：

You can use IIFE(Immediately Invoked Function Expression)and recursion to make it a little bit more easier:

您可以使用IIFE（立即调用函数表达式）和递归使其更容易一些：

var i = 5;  //set the countdown
(function timer(){
    if (--i < 0) return;
    setTimeout(function(){
        console.log(i + ' secs');  //do stuff here
        timer();
    }, 1000);
})();

var i = 5;
(function timer(){
    if (--i < 0) return;
    setTimeout(function(){
        document.getElementsByTagName('h1')[0].innerHTML = i + ' secs';
        timer();
    }, 1000);
})();

<h1>5 secs</h1>

回答by Kedarnath

// Javascript Countdown
// Version 1.01 6/7/07 (1/20/2000)
// by TDavid at http://www.tdscripts.com/
var now = new Date();
var theevent = new Date("Sep 29 2007 00:00:01");
var seconds = (theevent - now) / 1000;
var minutes = seconds / 60;
var hours = minutes / 60;
var days = hours / 24;
ID = window.setTimeout("update();", 1000);

function update() {
  now = new Date();
  seconds = (theevent - now) / 1000;
  seconds = Math.round(seconds);
  minutes = seconds / 60;
  minutes = Math.round(minutes);
  hours = minutes / 60;
  hours = Math.round(hours);
  days = hours / 24;
  days = Math.round(days);
  document.form1.days.value = days;
  document.form1.hours.value = hours;
  document.form1.minutes.value = minutes;
  document.form1.seconds.value = seconds;
  ID = window.setTimeout("update();", 1000);
}

<p><font face="Arial" size="3">Countdown To January 31, 2000, at 12:00: </font>
</p>
<form name="form1">
  <p>Days
    <input type="text" name="days" value="0" size="3">Hours
    <input type="text" name="hours" value="0" size="4">Minutes
    <input type="text" name="minutes" value="0" size="7">Seconds
    <input type="text" name="seconds" value="0" size="7">
  </p>
</form>

回答by Patrick Knott

Expanding upon the accepted answer, your machine going to sleep, etc. may delay the timer from working. You can get a true time, at the cost of a little processing. This will give a true time left.

扩展接受的答案，您的机器进入睡眠状态等可能会延迟计时器的工作。你可以得到一个真正的时间，代价是一点点处理。这将给出真正的剩余时间。

<span id="timer"></span>

<script>
var now = new Date();
var timeup = now.setSeconds(now.getSeconds() + 30);
//var timeup = now.setHours(now.getHours() + 1);

var counter = setInterval(timer, 1000);

function timer() {
  now = new Date();
  count = Math.round((timeup - now)/1000);
  if (now > timeup) {
      window.location = "/logout"; //or somethin'
      clearInterval(counter);
      return;
  }
  var seconds = Math.floor((count%60));
  var minutes = Math.floor((count/60) % 60);
  document.getElementById("timer").innerHTML = minutes + ":" + seconds;
}
</script>

回答by Aiwatko

Based on the solution presented by @Layton Everson I developed a counter including hours, minutes and seconds:

基于@Layton Everson 提出的解决方案，我开发了一个包括小时、分钟和秒的计数器：

var initialSecs = 86400;
var currentSecs = initialSecs;

setTimeout(decrement,1000); 

function decrement() {
   var displayedSecs = currentSecs % 60;
   var displayedMin = Math.floor(currentSecs / 60) % 60;
   var displayedHrs = Math.floor(currentSecs / 60 /60);

    if(displayedMin <= 9) displayedMin = "0" + displayedMin;
    if(displayedSecs <= 9) displayedSecs = "0" + displayedSecs;
    currentSecs--;
    document.getElementById("timerText").innerHTML = displayedHrs + ":" + displayedMin + ":" + displayedSecs;
    if(currentSecs !== -1) setTimeout(decrement,1000);
}

回答by maztt

// Javascript Countdown
// Version 1.01 6/7/07 (1/20/2000)
// by TDavid at http://www.tdscripts.com/
var now = new Date();
var theevent = new Date("Nov 13 2017 22:05:01");
var seconds = (theevent - now) / 1000;
var minutes = seconds / 60;
var hours = minutes / 60;
var days = hours / 24;
ID = window.setTimeout("update();", 1000);

function update() {
  now = new Date();
  seconds = (theevent - now) / 1000;
  seconds = Math.round(seconds);
  minutes = seconds / 60;
  minutes = Math.round(minutes);
  hours = minutes / 60;
  hours = Math.round(hours);
  days = hours / 24;
  days = Math.round(days);
  document.form1.days.value = days;
  document.form1.hours.value = hours;
  document.form1.minutes.value = minutes;
  document.form1.seconds.value = seconds;
  ID = window.setTimeout("update();", 1000);
}

<p><font face="Arial" size="3">Countdown To January 31, 2000, at 12:00: </font>
</p>
<form name="form1">
  <p>Days
    <input type="text" name="days" value="0" size="3">Hours
    <input type="text" name="hours" value="0" size="4">Minutes
    <input type="text" name="minutes" value="0" size="7">Seconds
    <input type="text" name="seconds" value="0" size="7">
  </p>
</form>

回答by nikksan

My solution works with MySQL date time formats and provides a callback function. on complition. Disclaimer: works only with minutes and seconds, as this is what I needed.

我的解决方案适用于 MySQL 日期时间格式并提供回调函数。在完成。 免责声明：仅适用于分钟和秒，因为这是我需要的。

jQuery.fn.countDownTimer = function(futureDate, callback){
    if(!futureDate){
        throw 'Invalid date!';
    }

    var currentTs = +new Date();
    var futureDateTs = +new Date(futureDate);

    if(futureDateTs <= currentTs){
        throw 'Invalid date!';
    }


    var diff = Math.round((futureDateTs - currentTs) / 1000);
    var that = this;

    (function countdownLoop(){
        // Get hours/minutes from timestamp
        var m = Math.floor(diff % 3600 / 60);
        var s = Math.floor(diff % 3600 % 60);
        var text = zeroPad(m, 2) + ':' + zeroPad(s, 2);

        $(that).text(text);

        if(diff <= 0){
            typeof callback === 'function' ? callback.call(that) : void(0);
            return;
        }

        diff--;
        setTimeout(countdownLoop, 1000);
    })();

    function zeroPad(num, places) {
      var zero = places - num.toString().length + 1;
      return Array(+(zero > 0 && zero)).join("0") + num;
    }
}

// $('.heading').countDownTimer('2018-04-02 16:00:59', function(){ // on complete})