Develop Reference

How to stop a function after ten seconds?

I found this piece of code while trying to find out a way to load a reddit page so that I can use ctrl + f to find a specific post. The problem is that it just keeps scrolling down and loading the pages. I need to find a way to stop it after 10 seconds so that I can take a look at what I loaded. Also I don't know any javascript so I couldn't really find anythig that would help me.
Here is the code
var lastScrollHeight = 0;
function autoScroll() {
var sh = document.documentElement.scrollHeight;
if (sh != lastScrollHeight) {
lastScrollHeight = sh;
document.documentElement.scrollTop = sh;
}
}
window.setInterval(autoScroll, 100);
I just paste that into the firefox console.

The setInterval() function returns an ID, which you can use to stop it.
Just put it in setTimeout() method like this:
var myInterval = setInterval(autoscroll, 100);
setTimeout(function(){ clearInterval(myInterval); }, 10000);

To stop the interval after a certain amount of time use a setTimeout() that calls clearInterval(). Here's a simplified version (with the time reduced to 1 second for demo purposes) that should help:
function autoScroll(){
console.log("running")
}
// save a reference to the interval handle
let interval = window.setInterval(autoScroll, 100);
// cancel interval after 1 second (1000 ms)
setTimeout(() => clearInterval(interval), 1000)

You will simply need to call clearInterval on your looped function to stop it after using a setTimeout set to 10 seconds, here is how you can implement it :
var lastScrollHeight = 0;
function autoScroll() {
var sh = document.documentElement.scrollHeight;
if (sh != lastScrollHeight) {
lastScrollHeight = sh;
document.documentElement.scrollTop = sh;
}
}
const interval = window.setInterval(autoScroll, 100);
window.setTimeout(() => {clearInterval(interval)}, 10000);

....
var intervalID = window.setInterval(autoScroll, 100);
setTimeout(function(){
clearInterval(intervalID);
}, 10000);

You can use setTimeout to call the function until 10s are up.
Here's an immediately-invoked function that calls itself every 100th sec until 10s has been reached.
(function autoScroll(t) {
t = t || 0;
if (t < 10000) {
console.log(t);
setTimeout(autoScroll, 100, t += 100);
}
})();

How do I delay this code running in JavaScript?

I have written this code to change an image:
change = function(){
for (r=0; r<6; r++){
for (i = 0; i < 6 ; i++) {
setInterval(imgfile(number=i+1), 5000);
}
}
}
imgfile= function(number){
a = 'document.getElementById("imgdiv").src = "images/'+number+'.svg"';
eval(a);
}
The function change() is called when a button is clicked.
When I press the button the image changes straight to 6.svg, when I want it to go through the images 1, 2, 3, 4, 5, 6 and to repeat it 6 times. When I change setInterval to change.setInterval or imgfile.setInterval it doesn't work at all. How do I fix this?

change = function(i=0){
imgfile(i%6+1);//change image
if(i<36) setTimeout(change,5000,i+1);//next image in 5 seconds
}
imgfile= function(number){
document.getElementById("imgdiv").src = "images/"+number+".svg";//no need to use ev(i||a)l
}
Instead of loop/interval mess you can simply start a timeout that restarts itself after changing the image... This code will loop over 6 images with a delay of 5 seconds and that 6 times...

Something like this, perhaps?
var index, imgCount, loopCount, imgTag, countdown;
index = 0;
imgCount = 6;
loopCount = 6;
imgTag = document.getElementById('imgdiv');
countdown = function () {
if (index < imgCount * loopCount) {
imgTag.src = 'images/' + index % imgCount + '.svg';
index = index + 1;
setTimeout(countdown, 5000);
}
};
countdown();
Here we're avoiding the double loop and using modular math (index % imgCount) to get the right file number.

For another question I wrote a nice utility function that has quite a number of uses, but can also handle this scenario very easily. The main issue is that there is no time elapsing between the different delays being set. So you are setting 6 different actions to all happen within 5000ms, and all will occur at the same moment.
Here's my original answer
Here's the utility function for that answer, along with its application to your problem.
function doHeavyTask(params) {
var totalMillisAllotted = params.totalMillisAllotted;
var totalTasks = params.totalTasks;
var tasksPerTick = params.tasksPerTick;
var tasksCompleted = 0;
var totalTicks = Math.ceil(totalTasks / tasksPerTick);
var initialDelay = params.initialDelay;
var interval = null;
if (totalTicks === 0) return;
var doTick = function() {
var totalByEndOfTick = Math.min(tasksCompleted + tasksPerTick, totalTasks);
do {
params.task(tasksCompleted++);
} while(tasksCompleted < totalByEndOfTick);
if (tasksCompleted >= totalTasks) clearInterval(interval);
};
// Tick once immediately, and then as many times as needed using setInterval
if (!initialDelay) doTick();
if (tasksCompleted < totalTicks) interval = setInterval(doTick, totalMillisAllotted / totalTicks);
}
// Do 6 actions over the course of 5000 x 6 milliseconds
doHeavyTask({
totalMillisAllotted: 5000 * 6,
totalTasks: 6,
tasksPerTick: 1,
initialDelay: false, // Controls if the 1st tick should occur immediately
task: function(n) { console.log('Set image to "images/' + (n + 1) + '.svg"'); }
});

You want to do setTimeout().
setTimeout pauses for the millesecond value and then does the code. Where setInterval runs the code every whatever milleseconds.
Yeah, don't do change.setInterval or whatever, it is just setInterval.
An example for you would be this inside the for loop to replace the setInterval function.
setTimeout(imgfile(i+1), 5000);

Javascript setInterval for sequential numbers

I'm writing some code that looks like this
<script type="text/javascript">
setInterval(function write_numbers(){
var count = 1;
var brk = "<br>"
while (count < 1218){
document.write(count + brk);
count++;
}},1000)
</script>
I need it to display the first number which is one then wait one second then display the next number (2) then wait a second, I need this to carry on till it reaches 1218 then stop.
With the code I've written it just writes all the numbers up, waits a second then repeats all the numbers again.
I'm quite new to coding so i don't know how to fix this.
If someone could tell me how to do it, it would be greatly appreciated.

There are multiple issues in your code, although you are using setInterval(), since you have a while loop inside it, the complete loop will be executed every 1 second.
Instead you need to have the setInterval() callback use an if statement to check whether to print the value or not like
var count = 1;
var interval = setInterval(function write_numbers() {
if (count <= 1218) {
document.body.appendChild(document.createTextNode(count));
document.body.appendChild(document.createElement('br'));
count++;
} else {
clearInterval(interval);
}
}, 1000)

The below script should do the trick for you:
<script>
var count = 1;
var brk = "<br>";
var myVar = setInterval(function(){ myTimer() }, 1000); // This should be a global variable for clearInterval to access it.
function myTimer() {
document.write(count + brk);
count++;
if(count > 1218){
myStopFunction();
}
}
function myStopFunction() {
clearInterval(myVar);
}
</script>

two issues
1) If you are using setInterval then you must clear the interval as well otherwise it will be an infinite loop
2) use if rather than while so that number is printed one by one.
try this
var count = 1;
var interval1= setInterval(function write_numbers(){
var brk = "<br>"
if (count < 1218)
{
document.write(count + brk);
count++;
}
else
{
count = 1;
clearInterval(interval1);
}
},1000);

First, you should define count outside setInterval. Defining inside will reset it every time.
Second, while (count < 1218){} should be a conditional statement. I have considered if(count>= 1218) as termination condition.
Third, when even you use setInterval, remember to use clearInterval as well.
Code
var count = 1;
var interval = setInterval(function write_numbers() {
var brk = "<br>"
document.write(count + brk);
count++;
if (count >= 10) {
window.clearInterval(interval);
}
}, 1000)

Try this code man , only one change from your code.
count variable declare out side of the setInterval function
<script type="text/javascript">
var count = 1;
setInterval(function write_numbers(){
var brk = "<br>"
if (count < 1218)
{
document.write(count + brk);
count++;
}
},1000);
</script>

clearInterval stopping setInterval working purely time based

I'm newbie in JS/jQuery, and got quite confused about the usage of stopping a setInterval function from running in x ms (or after running X times), which apparently happens with clearInterval. I know this question was asked similarly before, but couldn't help me.
As you see, it starts with 1000ms delay, and then repeat for 9000ms (or after running 3 times if better??), and then it needs to stop. What's the most ideal way of doing this? I couldn't properly use the clearInterval function. Thanks for the answers!
var elem = $('.someclass');
setTimeout(function() {
setInterval(function() {
elem.fadeOut(1500);
elem.fadeIn(1500);
},3000);
},1000);

To stop the interval you need to keep the handle that setInterval returns:
setTimeout(function() {
var cnt = 0;
var handle = setInterval(function() {
elem.fadeOut(1500);
elem.fadeIn(1500);
if (++cnt == 3) clearInterval(handle);
},3000);
},1000);

Create a counter, and keep a reference to your interval. When the counter hits 3, clear the interval:
var elem = $('.someclass');
setTimeout(function() {
var counter = 0;
var i = setInterval(function() {
elem.fadeOut(1500);
elem.fadeIn(1500);
counter++;
if (counter == 3)
clearInterval(i);
},3000);
},1000);

Given what you are trying to do is quite static, why not simply add delays and forget all the timers.:
var elem = $('.someclass');
elemt.delay(1000).fadeOut(1500).fadeIn(1500).delay(3000).fadeOut(1500).fadeIn(1500).delay(3000).fadeOut(1500).fadeIn(1500).delay(3000);
Or run the above in a small loop if you want to reduce the code size:
elemt.delay(1000);
for (var i = 0; i < 3; i++){
elemt.fadeOut(1500).fadeIn(1500).delay(3000);
}

You just need to clear the interval after three times:
setTimeout(function() {
var times = 0;
var interval = setInterval(function() {
elem.fadeOut(1500);
elem.fadeIn(1500);
if (++times > 3) clearInterval(interval);
},3000);
},1000);

How to create pause or delay in FOR loop?

I am working on a website, where I need to create a pause or delay.
So please tell me How to create pause or delay in for loop in javascript or jQuery
This is a test example
var s = document.getElementById("div1");
for (i = 0; i < 10; i++) {
s.innerHTML = s.innerHTML + i.toString();
//create a pause of 2 seconds.
}

You can't use a delay in the function, because then the change that you do to the element would not show up until you exit the function.
Use the setTimeout to run pieces of code at a later time:
var s = document.getElementById("div1");
for (i = 0; i < 10; i++) {
// create a closure to preserve the value of "i"
(function(i){
window.setTimeout(function(){
s.innerHTML = s.innerHTML + i.toString();
}, i * 2000);
}(i));
}

var wonderfulFunction = function(i) {
var s = document.getElementById("div1"); //you could pass this element as a parameter as well
i = i || 0;
if(i < 10) {
s.innerHTML = s.innerHTML + i.toString();
i++;
//create a pause of 2 seconds.
setTimeout(function() { wonderfulFunction(i) }, 2000);
}
}
//first call
wonderfulFunction(); //or wonderfulFunction(0);
You can't pause javascript code, the whole language is made to work with events, the solution I provided let's you execute the function with some delay, but the execution never stops.

I tried all one, but I think this code is better one, it is very simple code.
var s = document.getElementById("div1");
var i = 0;
setInterval(function () {s.innerHTML = s.innerHTML + i.toString(); i++;}, 2000);

if you want to create pause or delay in FOR loop,the only real method is
while (true) {
if( new Date()-startTime >= 2000) {
break;
}
}
the startTime is the time before you run the while
but this method will cause the browsers become very slow

It is impossible to directly pause a Javascript function within a for loop then later resume at that point.

This is how you should do it
var i = 0;
setTimeout(function() {
s.innerHTML = s.innerHTML + i.toString();
i++;
},2000);

The following code is an example of pseudo-multithreading that you can do in JS, it's roughly an example of how you can delay each iteration of a loop:
var counter = 0;
// A single iteration of your loop
// log the current value of counter as an example
// then wait before doing the next iteration
function printCounter() {
console.log(counter);
counter++;
if (counter < 10)
setTimeout(printCounter, 1000);
}
// Start the loop
printCounter();

While several of the other answers would work, I find the code to be less elegant. The Frame.js library was designed to solve this problem exactly. Using Frame you could do it like this:
var s = document.getElementById("div1");
for (i = 0; i < 10; i++) {
Frame(2000, function(callback){ // each iteration would pause by 2 secs
s.innerHTML = s.innerHTML + i.toString();
callback();
});
}
Frame.start();
In this case, it is nearly the same as the examples that use setTimeout, but Frame offers a lot of advantages, especially if the you are trying to do multiple or nested timeouts, or have a larger JS application that the timeouts need to work within.

I am executing a function where I need access to the outside object properties. So, the closure in Guffa solution doesn't work for me. I found a variation of nicosantangelo solution by simply wrapping the setTimeout in an if statement so it doesn't run forever.
var i = 0;
function test(){
rootObj.arrayOfObj[i].someFunction();
i++;
if( i < rootObj.arrayOfObj.length ){
setTimeout(test, 50 ); //50ms delay
}
}
test();

The way I found was to simply use setInterval() to loop instead. Here's my code example :
var i = 0;
var inte = setInterval(() => {
doSomething();
if (i == 9) clearInterval(inte);
i++;
}, 1000);
function doSomething() {
console.log(i);
};
This loops from 0 to 9 waiting 1 second in between each iteration.
Output :
0 1 2 3 4 5 6 7 8 9

It is not possible to pause a loop. However you can delay the execution of code fragments with the setTimeout() function. It would not make a lot of sense to pause the entire execution anyway.

I am using while loop and check the pause variable to check the user pause/resume the code.
var pause = false;
(async () => {
for (let index = 0; index < 1000; index++) {
while (pause) {
await new Promise((res) => setTimeout(res, 1000));
console.log("waiting");
}
await new Promise((res) => setTimeout(res, 1000));
console.log(index);
}
})();
const pausefunc = async () => {
pause = true;
};
const playfunc = () => {
pause = false;
};
<button onclick="playfunc()">Play</button>
<button onclick="pausefunc()">Pause</button>

I used a do...while loop to put a delay in my code for a modal dialog that was closing too quickly.
your stuff....
var tNow = Date.now();
var dateDiff = 0;
do {
dateDiff = Date.now() - tNow;
} while (dateDiff < 1000); //milliseconds - 2000 = 2 seconds
your stuff....