如何暂停 setInterval() 函数?

问题描述 投票:0回答:11

如何使用 Javascript 暂停和恢复 setInterval() 函数?

例如,也许我有一个秒表可以告诉你你浏览网页的秒数。有一个“暂停”和“恢复”按钮。 clearInterval()在这里不起作用的原因是因为如果用户在第40秒和第800毫秒点击“暂停”按钮,当他点击“恢复”按钮时,经过的秒数必须增加200 毫秒后为 1。如果我在计时器变量上使用clearInterval()函数(当单击暂停按钮时),然后再次在计时器变量上使用setInterval()函数(当单击恢复按钮时),经过的秒数将增加1 仅在 1000 毫秒后,这破坏了秒表的准确性。

那么我该怎么做呢?

javascript setinterval
11个回答
154
投票

您可以使用标志来跟踪状态:

var output = $('h1');
var isPaused = false;
var time = 0;
var t = window.setInterval(function() {
  if(!isPaused) {
    time++;
    output.text("Seconds: " + time);
  }
}, 1000);

//with jquery
$('.pause').on('click', function(e) {
  e.preventDefault();
  isPaused = true;
});

$('.play').on('click', function(e) {
  e.preventDefault();
  isPaused = false;
});
h1 {
    font-family: Helvetica, Verdana, sans-serif;
    font-size: 12px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h1>Seconds: 0</h1>
<button class="play">Play</button>
<button class="pause">Pause</button>

这正是我要做的,我不确定你是否真的可以暂停 setInterval。

注意:这个系统很简单,对于不需要高精度的应用程序来说效果很好,但它不会考虑滴答之间经过的时间:如果您在半秒后单击暂停,然后单击播放您的时间将缩短半秒。


19
投票

您不应该在间隔函数中测量时间。相反,只需在计时器启动时节省时间并在计时器停止/暂停时测量差异。仅使用 setInterval 来更新显示值。因此无需暂停计时器,您将通过这种方式获得最佳的准确性。


12
投票

虽然@Jonas Giuro 说得对:

您无法暂停 setInterval 函数,您可以停止它(clearInterval),或者让它运行

另一方面,可以使用 @VitaliyG 建议的方法来模拟这种行为

您不应该在间隔函数中测量时间。相反,只需在计时器启动时节省时间并在计时器停止/暂停时测量差异。仅使用 setInterval 来更新显示值。

var output = $('h1');
var isPaused = false;
var time = new Date();
var offset = 0;
var t = window.setInterval(function() {
  if(!isPaused) {
    var milisec = offset + (new Date()).getTime() - time.getTime();
    output.text(parseInt(milisec / 1000) + "s " + (milisec % 1000));
  }
}, 10);

//with jquery
$('.toggle').on('click', function(e) {
  e.preventDefault();
  isPaused = !isPaused;
  if (isPaused) {
    offset += (new Date()).getTime() - time.getTime();
  } else {
    time = new Date();
  }

});
h1 {
    font-family: Helvetica, Verdana, sans-serif;
    font-size: 12px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h1>Seconds: 0</h1>
<button class="toggle">Toggle</button>


10
投票

我写了一个简单的 ES6 类,可能会派上用场。 灵感来自https://stackoverflow.com/a/58580918/4907364答案

export class IntervalTimer {
    callbackStartTime;
    remaining = 0;
    paused = false;
    timerId = null;
    _callback;
    _delay;

    constructor(callback, delay) {
        this._callback = callback;
        this._delay = delay;
    }

    pause() {
        if (!this.paused) {
            this.clear();
            this.remaining = new Date().getTime() - this.callbackStartTime;
            this.paused = true;
        }
    }

    resume() {
        if (this.paused) {
            if (this.remaining) {
                setTimeout(() => {
                    this.run();
                    this.paused = false;
                    this.start();
                }, this.remaining);
            } else {
                this.paused = false;
                this.start();
            }
        }
    }

    clear() {
        clearInterval(this.timerId);
    }

    start() {
        this.clear();
        this.timerId = setInterval(() => {


            this.run();
        }, this._delay);
    }

    run() {
        this.callbackStartTime = new Date().getTime();
        this._callback();
    }
}

使用方法非常简单,

const interval = new IntervalTimer(console.log('aaa'), 3000);
interval.start();
interval.pause();
interval.resume();
interval.clear();

8
投票

为什么不使用更简单的方法呢?添加班级!

只需添加一个类来告诉间隔不要执行任何操作。例如:悬停时。

var i = 0;
this.setInterval(function() {
  if(!$('#counter').hasClass('pauseInterval')) { //only run if it hasn't got this class 'pauseInterval'
    console.log('Counting...');
    $('#counter').html(i++); //just for explaining and showing
  } else {
    console.log('Stopped counting');
  }
}, 500);

/* In this example, I'm adding a class on mouseover and remove it again on mouseleave. You can of course do pretty much whatever you like */
$('#counter').hover(function() { //mouse enter
    $(this).addClass('pauseInterval');
  },function() { //mouse leave
    $(this).removeClass('pauseInterval');
  }
);

/* Other example */
$('#pauseInterval').click(function() {
  $('#counter').toggleClass('pauseInterval');
});
body {
  background-color: #eee;
  font-family: Calibri, Arial, sans-serif;
}
#counter {
  width: 50%;
  background: #ddd;
  border: 2px solid #009afd;
  border-radius: 5px;
  padding: 5px;
  text-align: center;
  transition: .3s;
  margin: 0 auto;
}
#counter.pauseInterval {
  border-color: red;  
}
<!-- you'll need jQuery for this. If you really want a vanilla version, ask -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>


<p id="counter">&nbsp;</p>
<button id="pauseInterval">Pause</button></p>

我多年来一直在寻找这种快速且简单的方法,因此我发布了多个版本以向尽可能多的人介绍它。


5
投票

我知道这个线程很旧,但这可能是另一个解决方案:

var do_this = null;

function y(){
   // what you wanna do
}

do_this = setInterval(y, 1000);

function y_start(){
    do_this = setInterval(y, 1000);
};
function y_stop(){
    do_this = clearInterval(do_this);
};

5
投票

我的简单方法:

function Timer (callback, delay) {
  let callbackStartTime
  let remaining = 0

  this.timerId = null
  this.paused = false

  this.pause = () => {
    this.clear()
    remaining -= Date.now() - callbackStartTime
    this.paused = true
  }
  this.resume = () => {
    window.setTimeout(this.setTimeout.bind(this), remaining)
    this.paused = false
  }
  this.setTimeout = () => {
    this.clear()
    this.timerId = window.setInterval(() => {
      callbackStartTime = Date.now()
      callback()
    }, delay)
  }
  this.clear = () => {
    window.clearInterval(this.timerId)
  }

  this.setTimeout()
}

使用方法:

let seconds = 0
const timer = new Timer(() => {
  seconds++
  
  console.log('seconds', seconds)

  if (seconds === 8) {
    timer.clear()

    alert('Game over!')
  }
}, 1000)

timer.pause()
console.log('isPaused: ', timer.paused)

setTimeout(() => {
  timer.resume()
  console.log('isPaused: ', timer.paused)
}, 2500)


function Timer (callback, delay) {
  let callbackStartTime
  let remaining = 0

  this.timerId = null
  this.paused = false

  this.pause = () => {
    this.clear()
    remaining -= Date.now() - callbackStartTime
    this.paused = true
  }
  this.resume = () => {
    window.setTimeout(this.setTimeout.bind(this), remaining)
    this.paused = false
  }
  this.setTimeout = () => {
    this.clear()
    this.timerId = window.setInterval(() => {
      callbackStartTime = Date.now()
      callback()
    }, delay)
  }
  this.clear = () => {
    window.clearInterval(this.timerId)
  }

  this.setTimeout()
}

代码写得很快,没有重构,如果你想让我改进代码并给出ES2015版本(类),请提高我的答案的评级。


1
投票

以下代码提供了一种精确的方法来暂停和恢复计时器。

工作原理:

当计时器在暂停后恢复时,它会使用单个timeout生成一个

校正周期
,这将考虑暂停偏移(计时器在周期之间暂停的确切时间)。校正周期结束后,按规律
setInteval
调度后续周期,并继续正常周期执行。

这允许暂停/恢复计时器,而不会丢失同步。

代码:

function Timer(_fn_callback_ , _timer_freq_){
    let RESUME_CORRECTION_RATE = 2;

    let _timer_statusCode_;
    let _timer_clockRef_;

    let _time_ellapsed_;        // will store the total time ellapsed
    let _time_pause_;           // stores the time when timer is paused
    let _time_lastCycle_;       // stores the time of the last cycle

    let _isCorrectionCycle_;
 
    /**
     * execute in each clock cycle
     */
    const nextCycle = function(){
        // calculate deltaTime
        let _time_delta_        = new Date() - _time_lastCycle_;
        _time_lastCycle_    = new Date();
        _time_ellapsed_   += _time_delta_;

        // if its a correction cicle (caused by a pause,
        // destroy the temporary timeout and generate a definitive interval
        if( _isCorrectionCycle_ ){
            clearTimeout( _timer_clockRef_ );
            clearInterval( _timer_clockRef_ );
            _timer_clockRef_    = setInterval(  nextCycle , _timer_freq_  );
            _isCorrectionCycle_ = false;
        }
        // execute callback
        _fn_callback_.apply( timer, [ timer ] );
    };

    // initialize timer
    _time_ellapsed_     = 0;
    _time_lastCycle_     = new Date();
    _timer_statusCode_   = 1;
    _timer_clockRef_     = setInterval(  nextCycle , _timer_freq_  );


    // timer public API
    const timer = {
        get statusCode(){ return _timer_statusCode_ },
        get timestamp(){
            let abstime;
            if( _timer_statusCode_=== 1 ) abstime = _time_ellapsed_ + ( new Date() - _time_lastCycle_ );
            else if( _timer_statusCode_=== 2 ) abstime = _time_ellapsed_ + ( _time_pause_ - _time_lastCycle_ );
            return abstime || 0;
        },

        pause : function(){
            if( _timer_statusCode_ !== 1 ) return this;
            // stop timers
            clearTimeout( _timer_clockRef_ );
            clearInterval( _timer_clockRef_ );
            // set new status and store current time, it will be used on
            // resume to calculate how much time is left for next cycle
            // to be triggered
            _timer_statusCode_ = 2;
            _time_pause_       = new Date();
            return this;
        },

        resume: function(){
            if( _timer_statusCode_ !== 2 ) return this;
            _timer_statusCode_  = 1;
            _isCorrectionCycle_ = true;
            const delayEllapsedTime = _time_pause_ - _time_lastCycle_;
            _time_lastCycle_    = new Date( new Date() - (_time_pause_ - _time_lastCycle_) );

            _timer_clockRef_ = setTimeout(  nextCycle , _timer_freq_ - delayEllapsedTime - RESUME_CORRECTION_RATE);

            return this;
        } 
    };
    return timer;
};


let myTimer = Timer( x=> console.log(x.timestamp), 1000);
<input type="button" onclick="myTimer.pause()" value="pause">
<input type="button" onclick="myTimer.resume()" value="resume">

代码来源:

这个Timer是我自己创建的一个js库

advanced-timer
的修改和简化版本,有更多的功能。

完整的库和文档可在 NPMGITHUB

中找到

0
投票

let time = document.getElementById("time");
let stopButton = document.getElementById("stop");

let timeCount = 0,
  currentTimeout;

function play() {
  stopButton.hidden = false;
  clearInterval(currentTimeout);
  currentTimeout = setInterval(() => {
    timeCount++;
    const min = String(Math.trunc(timeCount / 60)).padStart(2, 0);
    const sec = String(Math.trunc(timeCount % 60)).padStart(2, 0);
    time.innerHTML = `${min} : ${sec}`;
  }, 1000);
}

function pause() {
  clearInterval(currentTimeout);
}

function stop() {
  stopButton.hidden = true;
  pause();
  timeCount = 0;
  time.innerHTML = `00 : 00`;
}
<div>
  <h1 id="time">00 : 00</h1>
  <br />
  <div>
    <button onclick="play()">play</button>
    <button onclick="pause()">pause</button>
    <button onclick="stop()" id="stop" hidden>Reset</button>
  </div>
</div>


0
投票

对于那些对替代方案感兴趣的人(例如,我的边缘情况是自动轮播功能的暂时暂停)。

您可以将间隔的创建放入一个函数中,并在一段时间后调用它以使用 setTimeout 重新启动它。

var carouselindex = 0,
    carouselinterval;

function changeoffset(dir) {
    // HTML Elements
    var container = document.getElementsByClassName("container")[0],
        indicator = document.getElementsByClassName("indicator")[0],
        width = container.offsetWidth,
        items = container.childElementCount;

    // Setting up index
    if (dir === '-' && carouselindex > 0) {
        carouselindex--;
    } else if (dir === '-' && carouselindex === 0) {
        carouselindex = (items - 1);
    } else if (dir === '+' && carouselindex < (items - 1)) {
        carouselindex++;
    } else if (dir === '+' && carouselindex === (items - 1)) {
        carouselindex = 0;
    }

    // Calculating offset
    var newoffset = Math.round(carouselindex * width),
        indicatoroffset = Math.round(carouselindex * 22);

    container.scrollTo(newoffset, 0);
    indicator.style.left = indicatoroffset + "px";
}

function startcarousel() {
    carouselinterval = setInterval(function() {
        changeoffset('+');
    }, 1000);
}

function pausecarousel(dir) {
    clearInterval(carouselinterval);
    changeoffset(dir);

    setTimeout(startcarousel, 5000);
}

startcarousel();

一些重要的注释可以消除任何困惑。我使用“+”或“-”来指示轮播应移动的方向,它们通常在变量 dir 中定义。

对于想了解启动和暂停 javascript Intervals 的人来说,唯一重要的部分是changeoffset 函数之外的代码。


0
投票

setInterval
包装器的另一个变体,在透明和一些测试演示上具有自删除功能。所有详细信息都在代码注释中。

// Function to set interval and controls
// Accepts fn to run and interval in ms
let Interval = (fn, ms) => {
  // Set flag
  let isPaused = false;
  // Set interval
  const interval = setInterval(() => !isPaused && fn(), ms);
  // Set internal methods
  Interval.pause = () => isPaused = true;
  Interval.resume = () => isPaused = false;
  Interval.isPaused = () => isPaused;
  // Set clear and self delete
  Interval.stop = () => {
    // Stop interval loop
    clearInterval(interval);
    // Check if self delete is possible
    // (Interval = const or let ?)
    try {
      Interval = undefined;
    } catch(err) {
      // Here you can print some warning
      // or leave muted
    }
  }
};

//
// Set interval
Interval(() => {
  console.log(new Date().toString());
}, 1000);

//
// TESTS
//
// Let's conduct some tests below
// Timeout helper function
const timeout = ms => new Promise(resolve => setTimeout(resolve, ms));

(async () => {

  //
  await timeout(3500);
  // Pause interval after 3,5 sec
  Interval.pause();

  //
  await timeout(3000);
  // Check pause state after +3 sec
  console.log(Interval.isPaused() ? `Interval is paused` : `Interval running`);

  //
  await timeout(3000);
  // Resume interval after +3 sec
  Interval.resume();

  //
  await timeout(3000);
  // Stop interval after +3 sec
  Interval.stop();
  console.log(`Interval stopped`);
  
  //
  await timeout(1000);
  // Check Interval internal method after +1 sec
  try {
    Interval.resume();
  } catch(err) {
    console.log(err.toString());
  }
})();

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