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Wrong use of Javascript setInterval()

I have a function called using setInterval of JavaScript, which in some scenarios is called multiple times without the interval gap defined (I suspect this is because the intervals are not cleared properly and I'm creating multiple intervals, but I'm not sure).
I can not reproduce the problem locally.
The code uses Twirl but it's basically JS:
function refreshCheckInRequests() {
if (interval) { // If there is an interval running stop it.
clearInterval(interval);
}
jsRoutes.controllers.ExtranetSecuredController.findPendingCheckInRequests("#gymId").ajax({ // Ajax call using Play Framework
success: function (data) {
$("#checkin-request-container").html(data);
addRowListeners()
},
error: function (data) {
if (data.status == 401) {
errorSwitchGym("#Messages("extranet.switch.gym")");
//location.reload();
}
else {
unexpectedError(data)
}
},
complete: function() {
interval = initInterval(); // At the end of the call init the interval again
}
});
}
function initInterval() {
return setInterval(function () { refreshCheckInRequests(); },
20000);
}
var interval;
refreshCheckInRequests();
$("#checkin-request-refresh").click(function (event) {
refreshCheckInRequests();
event.preventDefault();
});
I could use setTimeout instead because at the end, I always call refreshCheckInRequests once, I stop the interval, and at the end I create a new one.
If I use timeout I have to call again my function at the end of the execution of the callback of timeout (like I'm doing right now). If something goes wrong, my callback will never be called again.
Anyway, I would like to know what's going on here. Am I missing something? Am I doing something wrong? Any suggestions?

You're clearing the current interval every time refreshCheckInRequests is called, but there is a delay between when refreshCheckInRequests is called and the new interval is assigned. Because refreshCheckInRequests also runs when an element is clicked, the following scenario could result in an unterminated interval:
User clicks, current interval is cleared, asynchronous findPendingCheckInRequests runs
User clicks again, no interval currently exists (nothing to clear), another asynchronous findPendingCheckInRequests runs
Response from first findPendingCheckInRequests comes back. complete handler runs, interval is assigned to the new interval
Response from second findPendingCheckInRequests comes back. complete handler runs, interval is assigned to the new interval over the old interval
The first created interval remains running, but there no longer exists a reference to it, so that first interval continues repeating forever.
So, try clearing the interval at the moment you reassign interval, ensuring that every new interval will always clear the old one, if an old one is running:
complete: function() {
clearInterval(interval);
interval = initInterval();
}

Reset setTimeout after timer expires

I have an ongoing while loop. In the while loop, there is a setTimeout(). I want to reset the timer AFTER the timer expires. In other words, when timer expires, it should do some specified actions, and then freshly start the timer again.
For example, in the following code, %%--Hi--%% should be printed only ONCE in 5 seconds. However, after 5 seconds, %%--Hi--%% is printed continuously. I tried clearTimeout but it looks like that clearTimeout can stop timer only before timer expires.
while(){
var timeoutHandle = setTimeout(function() {
console.log("%%--Hi--%%");
clearTimeout(timeoutHandle);
},
5000); //5 sec
}
Help please! Thanks!

It's not the timeout that's tripping you up, it's the infinite while loop. You're effectively creating thousands of timeouts every second. Moving the timeout outside of the infinite loop should solve your problem.
function timedAction() {
// your timed actions to be invoked every 5 seconds
setTimeout(timedAction, 5000); // start the next timeout
}
setTimeout(timedAction, 5000); // start the first timeout
while() {
// your continuously executing actions
}
There is no need to clear a timeout after it expires.
Alternatively you could also use setInterval, simplifying your code as follows:
function timedAction() {
// your timed actions to be invoked every 5 seconds
}
setInterval(timedAction, 5000); // start the interval
while() {
// your continuously executing actions
}

try this code:
logFun();
function logFun() {
console.log("%%--Hi--%%");
setTimeout(logFun, 5000);
}
or, you can try setInterval:
setInterval(function () {
console.log("%%--Hi--%%");
}, 5000);

The setTimeout method does not act like a sleep statement. Your while loop will continue to iterate continuously regardless of what time interval you set in the setTimeout method.
You should remove the while and simply use setInterval(). (Mentioned in yibuyisheng's answer. +1)
var myInterval = setInterval(function () {
console.log("%%--Hi--%%");
}, 5000);
If you want to stop the interval, run the following:
clearInterval(myInterval);

Your problem is that setTimeout is an asynchronous function, so your code doesn't wait for it to finish before looping again. To get around this you have to create your new timer inside the previous timer.
Likewise you have to call any actions you want to execute from inside the timer and can't just call them from in the while loop, because they won't wait for the timer to finish.
function logFun() {
console.log("%%--Hi--%%");
// execute actions
setTimeout(logFun, 5000);
}
This is what yibuyisheng has done with his answer that just showed up. (Still posting because the answer was not explained.)

Alternatively, if you must create the setTimeout() from the while loop, you could have a boolean (true/false) lock it. This is not as clean as yibuyisheng's answer, but it also allows you to add as much logic as you'd like to control enabling and disabling the timeout.
Example:
window.isTimeoutLocked = false;
while(true) {
if (!window.isTimeoutLocked) {
var myFunction = function () {
console.log("%%--Hi--%%");
//The timeout has fired. Unlock it for the next one.
window.isTimeoutLocked = false;
}
window.setTimeout(myFunction, 5000);
//Timeout is queued. Lock this code until the timeout fires.
window.isTimeoutLocked = true;
}
}
Also, I doubt that an infinite while loop is best for your upstream code. There is probably a callback that you can hook into, like requestAnimationFrame or some relevant event.

JavaScript setTimeout() duplicates

I'm fairly new to JavaScript/jQuery, but have made a script to change the background picture.
First Script
The first script version works fine and does the following:
creates a setInterval timer that calls function backgroundChange() to run every 7 seconds
decides the next picture URL
sets the background picture
This works great, but the problem is when the website is live, on a slow connection the background picture doesn't load in time for the next timer change.
New Script
So the new version:
creates a setTimeout timer that calls function backgroundChange() to run after 7 seconds
var theTimer = setTimeout(backgroundChange, 7000);
clearsTimeout (surely I shouldn't have to run this?)
window.clearTimeout(theTimer);
decides the next picture URL
waits until the picture is loaded:
then sets the background picture
then adds a new setTimeout timer
$('#testImage').attr('src', imageText).load(function()
{
$('#backgroundTop').fadeIn(timeIn,function()
{
theTimer = setTimeout(backgroundTimer, 7000);
});
});
The problem is that the timer now seems to be called double the amount of times whenever the timer runs and exists in the .load function.
I havent purposely not posted my code yet, as I want to make sure my understanding is correct first, rather than someone just fixing my code.
Ta very much.

Instead of unbinding, you could use a JavaScript closure for the timer function. This will maintain a single timer that is reset every time it is called.
var slideTimer = (function(){
var timer = 0;
// Because the inner function is bound to the slideTimer variable,
// it will remain in score and will allow the timer variable to be manipulated.
return function(callback, ms){
clearTimeout (timer);
timer = setTimeout(callback, ms);
};
})();
Then in your code:
$('#testImage').attr('src', imageText).load(function() {
$('#backgroundTop').fadeIn(timeIn,function()
{
slideTimer(backgroundTimer, 7000);
});
});
There should be no need to clear or set the timer anywhere else in your code.

You need to unbind the load handler before you add the next one, since they keep piling up as your code stands. With every iteration, you add an extra handler that does the exact same thing. Use unbind to remove the old handler before you reattach:
$('#testImage').unbind('load');

Prevent and queue action (but only once globally) if previously called within X seconds

I always run into this problem and seem to implement a nasty looking solution.
It seems like a common design pattern to fire an action immediately, but not let that action queue up if clicked rapidly / delay firing if previously called within a timeframe. In my real world example, I have an AJAX call being made, so if I don't prevent repetitive actions the browser queues requests.
How would you implement this differently? What other options are there?
function myFunction() {
console.log("fired");
}
var timeout = null;
$("#foo").click(function() {
// if not previously clicked within 1 second, fire immediately
if (!timeout) {
myFunction();
timeout = setTimeout(function() {
timeout = null;
}, 1000);
} else {
// clicked again within 1s
clearTimeout(timeout); // clear it - we can't have multiple timeouts
timeout = setTimeout(function() {
myFunction();
timeout = null;
}, 1000);
};
});

With your current code, if you repeatedly click "#foo" at an interval slightly less than one second, say every 800ms, on first click it will fire the function immediately (obviously), but then it will fire the function exactly once more one second after the last click. That is, if you click ten times at 800ms intervals the function will fire once immediately and a second time approximately 8 seconds (800ms * 9 + 1000ms) after the first click.
I think you're better off removing the else case altogether, so that on click it will fire the function if it has not been called within the last second, otherwise it will do nothing with no attempt to queue another call up for later. Not only does that seem to me like a more logical way to operate, it halves the size of your function...
On the other hand, since you mentioned Ajax, rather than disabling the function based on a timer you may like to disable the function until the last Ajax request returns, i.e., use a flag similar to your timerid and reset it within an Ajax complete callback (noting that Ajax complete callbacks get called after success or failure of the request).
In the case of an auto-complete or auto-search function, where you want to send an Ajax request as the user types, you might want to remove the if case from your existing code and keep the else case, because for auto-complete you likely want to wait until after the user stops typing before sending the request - for that purpose I'd probably go with a shorter delay though, say 400 or 500ms.
Regarding general structure of the code, if I wanted a function to be fired a maximum of once per second I'd likely put that control into the function itself rather than in a click handler:
var myFunction = function() {
var timerid = null;
return function() {
if (timerid) return;
timerid = setTimeout(function(){ timerid=null; }, 1000);
// actual work of the function to be done here
console.log("myFunction fired");
};
}();
$("#foo").click(function() {
myFunction();
});
The immediately invoked anonymous function that I've added makes it uglier, but it keeps the timerid variable out of the global scope. If you don't like that obviously you could simply declare timerid in the same scope as myFunction() as you currently do.
This answer is getting kind of long, but if you have a lot of different functions that all need some kind of repeat control in them you could implement a single function to handle that part of it:
function limitRepeats(fn, delay) {
var timerid = null;
return function() {
if (timerid) return;
timerid = setTimeout(function(){ timerid = null; }, delay);
fn();
};
}
// myFunction1 can only be called once every 1000ms
var myFunction1 = limitRepeats(function() {
console.log("fired myFunction1()");
}, 1000);
// myFunction2 can only be called once every 3000ms
var myFunction2 = limitRepeats(function() {
console.log("fired myFunction2()");
}, 3000);
$("#foo").click(function() {
myFunction1();
myFunction2();
});

Javascript - Stop a repeating function [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
How to pause a setTimeout call ?
I have a function that gets called on page load which starts off a repeating function:
setTimeout(function () {
repeat();
}, 8000)
This function calls repeat() every 8 seconds, inside this function I have a bit of ajax which updates a counter on the page. Clicking on the counter gives the user a drop down menu with a number of messages. The counter value equals the number of messages the user has. Kind of like Facebook notifications.
When clicking the drop down menu Im using jQuery to hide and show it:
$('#messages').click(function () {
$('#messagesDropDown').slideDown();
})
.mouseleave(function () {
$('#messagesDropDown').slideUp();
});
When the #messagesDropDown is visible I want to stop the repeat() function, to prevent the list of messages from updating while Im viewing the current ones.
On .mouseleave I want to start the repeat() function again.
Anyone have any ideas how I can 'STOP' a repeating function In the .click function and start it again on .mouseleave ?

setTimeout returns a ID of the timeout. You can store that value, and then use clearTimeout to stop the timeout when you want.
var timeout;
$('#messages').click(function () {
$('#messagesDropDown').slideDown(function () {
clearTimeout(timeout); // Cancel the timeout when the slideDown has completed.
});
})
.mouseleave(function () {
$('#messagesDropDown').slideUp();
clearTimeout(timeout); // Cancel incase it's still running (you can also set `timeout` to undefined when you cancel with clearTimeout, and apply some logic here (`if (timeout == undefined)` so you can leave it running rather than restarting it)
timeout = setTimeout(repeat, 8000); // Store the ID of the timeout
});
setTimeout will not set a recurring event; it will only fire once (like a delayed event). Look at setInterval (and clearInterval) instead.

You said that this code starts a repeating function:
setTimeout(function () {
repeat();
}, 8000)
Since setTimeout doesn't repeat, I assume that the repeat function itself fires off another setTimeout to call itself again after it runs (chained setTimeout calls).
If so, you have two options:
Have a control variable telling repeat whether to do its work or not. A simple boolean will do. Set the boolean when you want repeat to skip its work, and have repeat check it. This is the dead simple answer.
Have control functions for repeat, like so:
var repeatHandle = 0;
function startRepeat() {
if (!repeatHandle) {
repeatHandle = setTimeout(repeatTick, 8000);
}
}
function repeatTick() {
repeatHandle = 0;
repeat();
}
function stopRepeat() {
if (repeatHandle) {
clearTimeout(repeatHandle);
repeatHandle = 0;
}
}
...and then use them to control the repeats. Be sure to modify repeat to call startRepeat to schedule its next call rather than calling setTimeout directly.