如何使用Javascript暂停和恢复setInterval()函数?
例如,也许我有一个秒表来告诉你你在网页上看到的秒数。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,经过的秒数必须在200毫秒后增加1。如果我在timer变量上使用clearInterval()函数(单击暂停按钮时),然后再次对timer变量使用setInterval()函数(单击恢复按钮时),经过的秒数将增加1仅在1000毫秒后,这会破坏秒表的准确性。
那我该怎么做?
答案 0 :(得分:87)
您可以使用标记来跟踪状态:
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>
这就是我要做的,我不确定你是否可以实际暂停setInterval。
注意:此系统非常简单,对于不需要高精度的应用程序非常有效,但它不会考虑时间间隔之间经过的时间:如果您在半秒后单击暂停,然后单击玩你的时间将关闭半秒钟。
答案 1 :(得分:8)
你不应该测量间隔功能的时间。而只是节省计时器启动时的时间,并在计时器停止/暂停时测量差异。仅使用setInterval更新显示的值。因此,无需暂停计时器,您将以这种方式获得最佳准确度。
答案 2 :(得分:6)
虽然@Jonas Giuro说的是对的:
你不能暂停setInterval函数,你可以将它停止(clearInterval),或让它运行
另一方面,可以使用approach @VitaliyG suggested模拟此行为:
您不应该在间隔函数中测量时间。而只是节省计时器启动时的时间,并在计时器停止/暂停时测量差异。仅使用setInterval更新显示的值。
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
$('.toggle').on('click', function(e) {
e.preventDefault();
isPaused = !isPaused;
if (isPaused) {
offset += (new Date()).getTime() - time.getTime();
} else {
time = new Date();
}
});
h1 {
font-family: Helvetica, Verdana, sans-serif;
font-size: 12px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h1>Seconds: 0</h1>
<button class="toggle">Toggle</button>
答案 3 :(得分:4)
只需添加一个告诉间隔不要做任何事情的类。例如:在悬停时。
var i = 0;
this.setInterval(function() {
if(!$('#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"> </p>
<button id="pauseInterval">Pause</button></p>
我一直在寻找这种快速简便的方法,所以我发布了几个版本,尽可能多地介绍它。
答案 4 :(得分:1)
我的简单方法:
table #mytable td {
background: #eee;
}
使用方法:
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()
}
代码编写迅速且未进行重构,如果您希望我改进代码并提供ES2015版本(类),请提高答案的等级。
答案 5 :(得分:1)
我写了一个简单的ES6类,可能会派上用场。 受https://stackoverflow.com/a/58580918/4907364答案
的启发export class IntervalTimer {
private callbackStartTime;
private remaining= 0;
private paused= false;
public timerId = null;
private readonly _callback;
private readonly _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);
}
private run() {
this.callbackStartTime = new Date().getTime();
this._callback();
}
}
用法非常简单,
const interval = new IntervalTimer(console.log(aaa), 3000);
interval.start();
interval.pause();
interval.resume();
interval.clear();
答案 6 :(得分:0)
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);
};
答案 7 :(得分:0)
以下代码提供了一种暂停计时器的精确方法。
工作方式:
当计时器暂停后恢复时,它会使用单个timeout
生成一个校正周期,该周期将考虑暂停偏移量(计时器在两个周期之间暂停)。校正周期结束后,它将使用常规setInteval
安排以下周期,并继续正常执行周期。
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">
代码源:
此Timer是advanced-timer
的修改和简化版本,list1 = [4,1,3]
list2 = [2,5,2]
list1_greater_list2_value = [a > b for a,b in zip(list1,list2)]
print ("list1-value greater then list2-value:", list1_greater_list2_value)
是我自己创建的js库,具有更多功能。
中