Develop Reference

Stopping a function from running

I have 3 sequential divs to display on a page, the page loads showing div 1, by going onto the 2nd it starts a timer, when that timer runs out it goes back to the first div. Navigating through to the next div should start the timer again. The timer function works OK on the first page but on the second page when it is called it is already running from the previous div and therefore ticks the time down twice as fast, and on the last div 3 times.
How can I get it to stop the currently running function then restart it?
Thanks,
$scope.timeLeft = 0;
var timeoutRunner = function (timerLength) {
$scope.timeLeft = timerLength;
var run = function () {
if ($scope.timeLeft >= 1) {
console.log($scope.timeLeft);
$scope.timeLeft--
$timeout(run, 1000);
} else if ($scope.timeLeft == 0){
$scope.endTransaction();
}
}
run();
}
timeoutRunner(5);

You need to add some logic that calls $timeout.cancel(timeoutRunner);.

Not sure where you want to cancel your timeout exactly (view change? when you end the transaction?) But here is how you would do it:
$scope.timeLeft = 0;
var timeoutPromise = false;
var timeoutRunner = function (timerLength) {
$scope.timeLeft = timerLength;
var run = function () {
if ($scope.timeLeft >= 1) {
console.log($scope.timeLeft);
$scope.timeLeft--
timeoutPromise = $timeout(run, 1000);
} else if ($scope.timeLeft == 0){
$scope.endTransaction();
$timeout.cancel(timeoutPromise);
}
}
run();
}
timeoutRunner(5);

Each time I called the function it created a new instance of it and I was unable to stop it on demand so I found a way to say which instance I want running:
$scope.timeLeft = 0;
var instanceRunning = 0;
var timeoutRunner = function (timerLength, instance) {
$scope.timeLeft = timerLength;
instanceRunning = instance;
var run = function () {
if (instanceRunning == instance){
if ($scope.timeLeft < 7 && $scope.timeLeft > 0){
$('#timer-container').show();
} else {
$('#timer-container').hide();
}
if ($scope.timeLeft >= 1) {
console.log($scope.timeLeft);
$scope.timeLeft--
$timeout(run, 1000);
} else if ($scope.timeLeft == 0){
$scope.endTransaction();
}
}
}
run();
}
timeoutRunner(20, 1);
timeoutRunner(20, 2);
timeoutRunner(20, 3);

Stopping timer not working:

I have THIS timer in my project.
When it runs out, it shows a Time Up screen, which works fine.
But when the player is Game Over, i show the Game Over screen, but the timer keeps running and when it hits 00:00 then it switches to the Time Up screen.
How can i make this timer stop counting down and set to 00:00 again?
I tried adding a function like this:
CountDownTimer.prototype.stop = function() {
diff = 0;
this.running = false;
};
I also tried to change the innerHTML but its obvious that its just changing the numbers without stopping the timer and after a second it will show the count down again... I don't know what to call.
//Crazy Timer function start
function CountDownTimer(duration, granularity) {
this.duration = duration;
this.granularity = granularity || 1000;
this.tickFtns = [];
this.running = false;
}
CountDownTimer.prototype.start = function() {
if (this.running) {
return;
}
this.running = true;
var start = Date.now(),
that = this,
diff, obj;
(function timer() {
diff = that.duration - (((Date.now() - start) / 1000) | 0);
if (diff > 0) {
setTimeout(timer, that.granularity);
} else {
diff = 0;
that.running = false;
}
obj = CountDownTimer.parse(diff);
that.tickFtns.forEach(function(ftn) {
ftn.call(this, obj.minutes, obj.seconds);
}, that);
}());
};
CountDownTimer.prototype.onTick = function(ftn) {
if (typeof ftn === 'function') {
this.tickFtns.push(ftn);
}
return this;
};
CountDownTimer.prototype.expired = function() {
return !this.running;
};
CountDownTimer.parse = function(seconds) {
return {
'minutes': (seconds / 60) | 0,
'seconds': (seconds % 60) | 0
};
};
window.onload = function () {
var display = document.querySelector('#countDown'),
timer = new CountDownTimer(timerValue),
timeObj = CountDownTimer.parse(timerValue);
format(timeObj.minutes, timeObj.seconds);
timer.onTick(format).onTick(checkTime);
document.querySelector('#startBtn').addEventListener('click', function () {
timer.start();
});
function format(minutes, seconds) {
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ':' + seconds;
}
function checkTime(){
if(this.expired()) {
timeUp();
document.querySelector('#startBtn').addEventListener('click', function () {
timer.start();
});
}
}
};

Instead of recursively calling setTimeout, try setInterval instead. You could then store a reference to the timer:
this.timer = setInterval(functionToRunAtInterval, this.granularity);
and kill it when the game finishes::
clearInterval(this.timer)
(see MDN's docs for more info on setInterval)

It's been a while and I'm not sure if you've figured it out but check out the fiddle below:
https://jsfiddle.net/f8rh3u85/1/
// until running is set to false the timer will keep running
if (that.running) {
if (diff > 0) {
setTimeout(timer, that.granularity);
} else {
diff = 0;
that.running = false;
}
obj = CountDownTimer.parse(diff);
that.tickFtns.forEach(function(ftn) {
ftn.call(this, obj.minutes, obj.seconds);
}, that);
}
I've added a button that causes running to be set to false which stops the timer.
Button:
<button id="stop">Game Over</button>
Code:
$( "#stop" ).click(function() {
timer.running = false;
});
So that should hopefully get you to where you need to be.

Similar to Tom Jenkins' answer, you need to cancel the next tick by avoiding the diff > 0 branch of your if statement. You could keep your code as it stands and use your suggested stop method, however, you'd need to change your logic around handling ticks to check that both running === true and a new param gameOver === false.
Ultimately, I think your problem is that no matter whether the timer is running or not, you'll always execute this code on a tick:
obj = CountDownTimer.parse(diff);
that.tickFtns.forEach(function(ftn) {
ftn.call(this, obj.minutes, obj.seconds);
}, that);
If you have a game over state, you probably don't want to call the provided callbacks, so add some conditional check in there.

countdown timer stops at zero i want it to reset

I am trying to figure out a way to make my countdown timer restart at 25 all over again when it reaches 0. I dont know what I am getting wrong but it wont work.
Javascript
window.onload = function() {
startCountDown(25, 1000, myFunction);
}
function startCountDown(i, p, f) {
var pause = p;
var fn = f;
var countDownObj = document.getElementById("countDown");
countDownObj.count = function(i) {
//write out count
countDownObj.innerHTML = i;
if (i == 0) {
//execute function
fn();
//stop
return;
}
setTimeout(function() {
// repeat
countDownObj.count(i - 1);
},
pause
);
}
//set it going
countDownObj.count(i);
}
function myFunction(){};
</script>
HTML
<div id="countDown"></div>

try this, timer restarts after 0
http://jsfiddle.net/GdkAH/1/
Full code:
window.onload = function() {
startCountDown(25, 1000, myFunction);
}
function startCountDown(i, p, f) {
var pause = p;
var fn = f;
var countDownObj = document.getElementById("countDown");
countDownObj.count = function(i) {
// write out count
countDownObj.innerHTML = i;
if (i == 0) {
// execute function
fn();
startCountDown(25, 1000, myFunction);
// stop
return;
}
setTimeout(function() {
// repeat
countDownObj.count(i - 1);
}, pause);
}
// set it going
countDownObj.count(i);
}
function myFunction(){};
​

I don't see you resetting the counter. When your counter goes down to 0, it executes the function and return. Instead, you want to execute the function -> reset the counter -> return
You can do this by simply adding i = 25 under fn() :
function startCountDown(i, p, f) {
var pause = p;
var fn = f;
var countDownObj = document.getElementById("countDown");
countDownObj.count = function(i) {
// write out count
countDownObj.innerHTML = i;
if (i == 0) {
// execute function
fn();
i = 25;
// stop
return;
}
setTimeout(function() {
// repeat
countDownObj.count(i - 1);
},
pause
);
}
// set it going

in #Muthu Kumaran code is not showing zero after countdown 1 . you can update to this:
if (i < 0) {
// execute function
fn();
startCountDown(10, 1000, myFunction);
// stop
return;
}

The main reason for using setInterval for a timer that runs continuously is to adjust the interval so that it updates as closely as possible to increments of the system clock, usually 1 second but maybe longer. In this case, that doesn't seem to be necessary, so just use setInterval.
Below is a function that doesn't add non–standard properties to the element, it could be called using a function expression from window.onload, so avoid global variables altogether (not that there is much point in that, but some like to minimise them).
var runTimer = (function() {
var element, count = 0;
return function(i, p, f) {
element = document.getElementById('countDown');
setInterval(function() {
element.innerHTML = i - (count % i);
if (count && !(count % i)) {
f();
}
count++;
}, p);
}
}());
function foo() {
console.log('foo');
}
window.onload = function() {
runTimer(25, 1000, foo);
}

Looping functions with timeout

I want to have two functions (an animation downwards and animation upwards) executing one after the other in a loop having a timeout of a few seconds between both animations. But I don't know how to say it in JS …
Here what I have so far:
Function 1
// Play the Peek animation - downwards
function peekTile() {
var peekAnimation = WinJS.UI.Animation.createPeekAnimation([tile1, tile2]);
// Reposition tiles to their desired post-animation position
tile1.style.top = "-150px";
tile2.style.top = "-150px";
peekAnimation.execute();
}
Function 2
// Play the Peek animation - upwards
function unpeekTile() {
var peekAnimation = WinJS.UI.Animation.createPeekAnimation([tile1, tile2]);
// Reposition tiles to their desired post-animation position
tile1.style.top = "0px";
tile2.style.top = "0px";
peekAnimation.execute();
}
And here's a sketch how both functions should be executed:
var page = WinJS.UI.Pages.define("/html/updateTile.html", {
ready: function (element, options) {
peekTile();
[timeOut]
unpeekTile();
[timeOut]
peekTile();
[timeOut]
unpeekTile();
[timeOut]
and so on …
}
});

You can do this using setTimeout or setInterval, so a simple function to do what you want is:
function cycleWithDelay() {
var delay = arguments[arguments.length - 1],
functions = Array.prototype.slice.call(arguments, 0, arguments.length - 1),
pos = 0;
return setInterval(function () {
functions[pos++]();
pos = pos % functions.length;
}, delay);
}
Usage would be like this for you:
var si = cycleWithDelay(peekTile, unpeekTile, 300);
and to stop it:
clearInterval(si);
This will just cycle through the functions calling the next one in the list every delay msec, repeating back at the beginning when the last one is called. This will result in your peekTile, wait, unpeekTile, wait, peekTile, etc.
If you prefer to start/stop at will, perhaps a more generic solution would suit you:
function Cycler(f) {
if (!(this instanceof Cycler)) {
// Force new
return new Cycler(arguments);
}
// Unbox args
if (f instanceof Function) {
this.fns = Array.prototype.slice.call(arguments);
} else if (f && f.length) {
this.fns = Array.prototype.slice.call(f);
} else {
throw new Error('Invalid arguments supplied to Cycler constructor.');
}
this.pos = 0;
}
Cycler.prototype.start = function (interval) {
var that = this;
interval = interval || 1000;
this.intervalId = setInterval(function () {
that.fns[that.pos++]();
that.pos %= that.fns.length;
}, interval);
}
Cycler.prototype.stop = function () {
if (null !== this.intervalId) {
clearInterval(this.intervalId);
this.intervalId = null;
}
}
Example usage:
var c = Cycler(peekTile, unpeekTile);
c.start();
// Future
c.stop();

You use setInterval() to call unpeekTile() every 1000 milliseconds and then you call setTimeOut() to run peekTile() after 1000 milliseconds at the end of the unpeekTile() function:
function peekTile() {
var peekAnimation = WinJS.UI.Animation.createPeekAnimation([tile1, tile2]);
// Reposition tiles to their desired post-animation position
tile1.style.top = "-150px";
tile2.style.top = "-150px";
peekAnimation.execute();
}
function unpeekTile() {
/* your code here */
setTimeout(peekTile, 1000);
}
setInterval(unpeekTile, 1000);

Check out the fiddle
var animation = (function () {
var peekInterval, unpeekInterval, delay;
return {
start: function (ip) {
delay = ip;
peekInterval = setTimeout(animation.peekTile, delay);
},
peekTile: function () {
//Your Code goes here
console.log('peek');
unpeekInterval = setTimeout(animation.unpeekTile, delay);
},
unpeekTile: function () {
//Your Code goes here
console.log('unpeek');
peekInterval = setTimeout(animation.peekTile, delay);
},
stop: function () {
clearTimeout(peekInterval);
clearTimeout(unpeekInterval);
}
}
})();
animation.start(1000);
// To stop
setTimeout(animation.stop, 3000);
​
I can't use this instead of animation.peekTile as setTimeout executes in global scope

How do I know when I've stopped scrolling?

How do I know when I've stopped scrolling using Javascript?

You can add an event handler for the scroll event and start a timeout. Something like:
var timer = null;
window.addEventListener('scroll', function() {
if(timer !== null) {
clearTimeout(timer);
}
timer = setTimeout(function() {
// do something
}, 150);
}, false);
This will start a timeout and wait 150ms. If a new scroll event occurred in the meantime, the timer is aborted and a new one is created. If not, the function will be executed. You probably have to adjust the timing.
Also note that IE uses a different way to attach event listeners, this should give a good introduction: quirksmode - Advanced event registration models

There isn't a "Stopped Scrolling" event. If you want to do something after the user has finished scrolling, you can set a timer in the "OnScroll" event. If you get another "OnScroll" event fired then reset the timer. When the timer finally does fire, then you can assume the scrolling has stopped. I would think 500 milliseconds would be a good duration to start with.
Here's some sample code that works in IE and Chrome:
<html>
<body onscroll="bodyScroll();">
<script language="javascript">
var scrollTimer = -1;
function bodyScroll() {
document.body.style.backgroundColor = "white";
if (scrollTimer != -1)
clearTimeout(scrollTimer);
scrollTimer = window.setTimeout("scrollFinished()", 500);
}
function scrollFinished() {
document.body.style.backgroundColor = "red";
}
</script>
<div style="height:2000px;">
Scroll the page down. The page will turn red when the scrolling has finished.
</div>
</body>
</html>

Here's a more modern, Promise-based solution I found on a repo called scroll-into-view-if-needed
Instead of using addEventListener on the scroll event it uses requestAnimationFrame to watch for frames with no movement and resolves when there have been 20 frames without movement.
function waitForScrollEnd () {
let last_changed_frame = 0
let last_x = window.scrollX
let last_y = window.scrollY
return new Promise( resolve => {
function tick(frames) {
// We requestAnimationFrame either for 500 frames or until 20 frames with
// no change have been observed.
if (frames >= 500 || frames - last_changed_frame > 20) {
resolve()
} else {
if (window.scrollX != last_x || window.scrollY != last_y) {
last_changed_frame = frames
last_x = window.scrollX
last_y = window.scrollY
}
requestAnimationFrame(tick.bind(null, frames + 1))
}
}
tick(0)
})
}
With async/await and then
await waitForScrollEnd()
waitForScrollEnd().then(() => { /* Do things */ })

(function( $ ) {
$(function() {
var $output = $( "#output" ),
scrolling = "<span id='scrolling'>Scrolling</span>",
stopped = "<span id='stopped'>Stopped</span>";
$( window ).scroll(function() {
$output.html( scrolling );
clearTimeout( $.data( this, "scrollCheck" ) );
$.data( this, "scrollCheck", setTimeout(function() {
$output.html( stopped );
}, 250) );
});
});
})( jQuery );
=======>>>>
Working Example here

I did something like this:
var scrollEvents = (function(document, $){
var d = {
scrolling: false,
scrollDirection : 'none',
scrollTop: 0,
eventRegister: {
scroll: [],
scrollToTop: [],
scrollToBottom: [],
scrollStarted: [],
scrollStopped: [],
scrollToTopStarted: [],
scrollToBottomStarted: []
},
getScrollTop: function(){
return d.scrollTop;
},
setScrollTop: function(y){
d.scrollTop = y;
},
isScrolling: function(){
return d.scrolling;
},
setScrolling: function(bool){
var oldVal = d.isScrolling();
d.scrolling = bool;
if(bool){
d.executeCallbacks('scroll');
if(oldVal !== bool){
d.executeCallbacks('scrollStarted');
}
}else{
d.executeCallbacks('scrollStopped');
}
},
getScrollDirection : function(){
return d.scrollDirection;
},
setScrollDirection : function(direction){
var oldDirection = d.getScrollDirection();
d.scrollDirection = direction;
if(direction === 'UP'){
d.executeCallbacks('scrollToTop');
if(direction !== oldDirection){
d.executeCallbacks('scrollToTopStarted');
}
}else if(direction === 'DOWN'){
d.executeCallbacks('scrollToBottom');
if(direction !== oldDirection){
d.executeCallbacks('scrollToBottomStarted');
}
}
},
init : function(){
d.setScrollTop($(document).scrollTop());
var timer = null;
$(window).scroll(function(){
d.setScrolling(true);
var x = d.getScrollTop();
setTimeout(function(){
var y = $(document).scrollTop();
d.setScrollTop(y);
if(x > y){
d.setScrollDirection('UP');
}else{
d.setScrollDirection('DOWN');
}
}, 100);
if(timer !== 'undefined' && timer !== null){
clearTimeout(timer);
}
timer = setTimeout(function(){
d.setScrolling(false);
d.setScrollDirection('NONE');
}, 200);
});
},
registerEvents : function(eventName, callback){
if(typeof eventName !== 'undefined' && typeof callback === 'function' && typeof d.eventRegister[eventName] !== 'undefined'){
d.eventRegister[eventName].push(callback);
}
},
executeCallbacks: function(eventName){
var callabacks = d.eventRegister[eventName];
for(var k in callabacks){
if(callabacks.hasOwnProperty(k)){
callabacks[k](d.getScrollTop());
}
}
}
};
return d;
})(document, $);
the code is available here: documentScrollEvents

Minor update in your answer. Use mouseover and out function.
$(document).ready(function() {
function ticker() {
$('#ticker li:first').slideUp(function() {
$(this).appendTo($('#ticker')).slideDown();
});
}
var ticke= setInterval(function(){
ticker();
}, 3000);
$('#ticker li').mouseover(function() {
clearInterval(ticke);
}).mouseout(function() {
ticke= setInterval(function(){ ticker(); }, 3000);
});
});
DEMO

I was trying too add a display:block property for social icons that was previously hidden on scroll event and then again hide after 2seconds. But
I too had a same problem as my code for timeout after first scroll would start automatically and did not had reset timeout idea. As it didn't had proper reset function.But after I saw David's idea on this question I was able to reset timeout even if someone again scrolled before actually completing previous timeout.
problem code shown below before solving
$(window).scroll(function(){
setTimeout(function(){
$('.fixed-class').slideUp('slow');
},2000);
});
edited and working code with reset timer if next scroll occurs before 2s
var timer=null;
$(window).scroll(function(){
$('.fixed-class').css("display", "block");
if(timer !== null) {
clearTimeout(timer);
}
timer=setTimeout(function(){
$('.fixed-class').slideUp('slow');
},2000);
});
My working code will trigger a hidden division of class named 'fixed-class' to show in block on every scroll. From start of latest scroll the timer will count 2 sec and then again change the display from block to hidden.

For more precision you can also check the scroll position:
function onScrollEndOnce(callback, target = null) {
let timeout
let targetTop
const startPosition = Math.ceil(document.documentElement.scrollTop)
if (target) {
targetTop = Math.ceil(target.getBoundingClientRect().top + document.documentElement.scrollTop)
}
function finish(removeEventListener = true) {
if (removeEventListener) {
window.removeEventListener('scroll', onScroll)
}
callback()
}
function isScrollReached() {
const currentPosition = Math.ceil(document.documentElement.scrollTop)
if (targetTop == null) {
return false
} else if (targetTop >= startPosition) {
return currentPosition >= targetTop
} else {
return currentPosition <= targetTop
}
}
function onScroll() {
if (timeout) {
clearTimeout(timeout)
}
if (isScrollReached()) {
finish()
} else {
timeout = setTimeout(finish, 500)
}
}
if (isScrollReached()) {
finish(false)
} else {
window.addEventListener('scroll', onScroll)
}
}
Usage example:
const target = document.querySelector('#some-element')
onScrollEndOnce(() => console.log('scroll end'), target)
window.scrollTo({
top: Math.ceil(target.getBoundingClientRect().top + document.documentElement.scrollTop),
behavior: 'smooth',
})

Here's an answer that doesn't use any sort of timer, thus in my case predicted when the scrolling actually ended, and is not just paused for a bit.
function detectScrollEnd(element, onEndHandler) {
let scrolling = false;
element.addEventListener('mouseup', detect);
element.addEventListener('scroll', detect);
function detect(e) {
if (e.type === 'scroll') {
scrolling = true;
} else {
if (scrolling) {
scrolling = false;
onEndHandler?.();
}
}
}
}