151

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

4

13 回答 13

258 
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
}

要使计时器的代码出现在段落中（或页面上的任何其他位置），只需输入以下行：

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

您希望秒数出现的位置。timer()然后在您的函数中插入以下行，如下所示：

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

 document.getElementById("timer").innerHTML=count + " secs"; // watch for spelling
}
于 2009-07-28T04:00:13.940 回答
105

我前段时间写了这个脚本：

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);
  };
}
于 2009-07-28T04:59:41.183 回答
56

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，那么它实际上会在 1008 左右。

这是您应该如何做的：

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
}

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!");
    }
);
于 2012-07-04T22:33:35.200 回答
21

如果有人需要分分钟和秒，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);
    }
于 2013-03-11T22:48:12.300 回答
3 

// 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>

于 2012-07-07T17:33:53.253 回答
3

刚刚修改了@ClickUpvote 的答案：

您可以使用IIFE（立即调用函数表达式）和递归使其更容易一点：

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>

于 2018-09-20T12:50:17.450 回答
2

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。你可以得到一个真实的时间，代价是一点处理。这将给出一个真正的剩余时间。

<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>
于 2017-10-19T19:18:40.130 回答
1

为了性能，我们现在可以安全地使用requestAnimationFrame进行快速循环，而不是 setInterval/setTimeout。

使用 setInterval/setTimeout 时，如果循环任务花费的时间超过了间隔，浏览器将简单地扩展间隔循环，以继续完整渲染。这是在制造问题。在 setInterval/setTimeout 过载几分钟后，这可能会冻结选项卡、浏览器或整个计算机。

互联网设备的性能范围很广，因此很难以毫秒为单位硬编码一个固定的间隔时间！

使用Date 对象，比较开始日期纪元和当前。这比其他任何事情都快，浏览器将以稳定的60FPS（1000 / 60 = 16.66 毫秒每帧）处理所有事情 -眨眼的四分之一- 如果循环中的任务需要更多，浏览器会丢弃一些重绘。

这允许在我们的眼睛注意到之前留出余量（人类 = 24FPS => 1000 / 24 = 41.66ms by frame = 流畅的动画！）

https://caniuse.com/#search=requestAnimationFrame

/* Seconds to (STRING)HH:MM:SS.MS ------------------------*/
/* This time format is compatible with FFMPEG ------------*/
function secToTimer(sec){
  const o = new Date(0), p =  new Date(sec * 1000)
  return new Date(p.getTime()-o.getTime()).toString().split(" ")[4] + "." + p.getMilliseconds()
}

/* Countdown loop ----------------------------------------*/
let job, origin = new Date().getTime()
const timer = () => {
  job = requestAnimationFrame(timer)
  OUT.textContent = secToTimer((new Date().getTime() - origin) / 1000)
}

/* Start looping -----------------------------------------*/
requestAnimationFrame(timer)

/* Stop looping ------------------------------------------*/
// cancelAnimationFrame(job)

/* Reset the start date ----------------------------------*/
// origin = new Date().getTime()
span {font-size:4rem}
<span id="OUT"></span>
<br>
<button onclick="origin = new Date().getTime()">RESET</button>
<button onclick="requestAnimationFrame(timer)">RESTART</button>
<button onclick="cancelAnimationFrame(job)">STOP</button>

于 2019-08-26T18:19:38.160 回答
0

您可以使用纯 JS 执行以下操作。您只需要为函数提供秒数，剩下的就交给它了。

var insertZero = n => n < 10 ? "0"+n : ""+n,
   displayTime = n => n ? time.textContent = insertZero(~~(n/3600)%3600) + ":" +
                                             insertZero(~~(n/60)%60) + ":" +
                                             insertZero(n%60)
                        : time.textContent = "IGNITION..!",
 countDownFrom = n => (displayTime(n), setTimeout(_ => n ? sid = countDownFrom(--n)
                                                         : displayTime(n), 1000)),
           sid;
countDownFrom(3610);
setTimeout(_ => clearTimeout(sid),20005);
<div id="time"></div>

于 2016-10-19T17:03:38.843 回答
0

基于@Layton Everson 提出的解决方案，我开发了一个包含小时、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);
}
于 2017-10-19T21:16:36.043 回答
0 

// 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>

于 2017-11-13T17:02:22.870 回答
0

我的解决方案适用于 MySQL 日期时间格式并提供回调函数。关于编译。 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})
于 2018-04-02T13:09:21.203 回答
0 
var hr = 0;
var min = 0;
var sec = 0;
var count = 0;
var flag = false;


function start(){
    flag = true;
    stopwatch();


}
function stop(){
    flag = false;

}

function reset(){
    flag = false;
    hr = 0;
    min = 0;
    sec = 0;
    count = 0;
    document.getElementById("hr").innerHTML = "00";
    document.getElementById("min").innerHTML = "00";
    document.getElementById("sec").innerHTML = "00";
    document.getElementById("count").innerHTML = "00";

}



function stopwatch(){
    if(flag == true){
        count = count + 1;
        setTimeout( 'stopwatch()', 10);

    if(count ==100){
        count =0;
        sec = sec +1;

    }
    }

    if(sec ==60){
        min = min +1 ;
        sec = 0;

    }
      if(min == 60){
        hr = hr +1 ;
        min = 0;
        sec = 0;

    }
    var hrs = hr;
    var mins = min;
    var secs = sec;
    if(hr<10){
        hrs ="0" + hr; 

    }
    if(min<10){
        mins ="0" + min; 

    }
   if(sec<10){
        secs ="0" + sec; 

    }
    document.getElementById("hr").innerHTML = hrs;
    document.getElementById("min").innerHTML = mins;
    document.getElementById("sec").innerHTML = secs;
    document.getElementById("count").innerHTML = count;
      
}
于 2021-09-14T06:18:37.680 回答