Develop Reference

clearTimeout not working on mouseup event

Why is timeout not being cleared in this setup? How can I make up() stop the delayed actions from running?
var active = false;
var delay;
window.addEventListener("mousedown", down, false);
window.addEventListener("mouseup", up, false);
window.addEventListener("mousemove", move, false);
function down(e) {
active = true;
console.log("down")
window.scrollTo(0,document.body.scrollHeight);
}
function up(e) {
active = false;
clearTimeout(delay); //expecting this to clear delay
console.log("up")
window.scrollTo(0,document.body.scrollHeight);
}
function move(e) {
if (active) {
delay = setTimeout(function() {
console.log("move")
window.scrollTo(0,document.body.scrollHeight);
}, 50);
}
}
Expecting delay to be cleared on mouseup but it still executes.

You keep making timeouts on every movement. It does not replace the last one...
Your code is basically this
delay = setTimeout(function() { } <-- will run
delay = setTimeout(function() { } <-- will run
delay = setTimeout(function() { } <-- will run
delay = setTimeout(function() { } <-- will run
delay = setTimeout(function() { } <-- will run
delay = setTimeout(function() { } <-- will run
delay = setTimeout(function() { } <-- cancels this one
window.clearTimeout(delay)
So you need to remove it before you create a new one
if (active) {
if (delay) window.clearTimeout(delay)
delay = setTimeout(function() {
console.log("move")
window.scrollTo(0,document.body.scrollHeight);
}, 50);
}
If you need to move to fire more than once, that you want to look into throttling scripts.

So, I've learned from the replies that setTimeout produces a new independent timer every time move() is executed. My understanding was that each new timer overwrites the previous one but as this is not the case I had to think of something else.
I did't really explain what I actually needed to achieve with the delay so let me clarify. I want to create a timeout for an action if that action has not been executed for x amount of time. Using setTimeout on the action it self created the problem that the action would still potentially have multiple queued executions waiting to happen even after mouseup events.
So instead I used setTimeout on a new variable that acts as a lock to the action. The result is the following code:
var active = false;
var actionTimeout = false;
var actionTimeStamp;
var actionLock = false;
window.addEventListener("mousedown", down, false);
window.addEventListener("mouseup", up, false);
window.addEventListener("mousemove", move, false);
function down(e) {
active = true;
console.log("down")
window.scrollTo(0,document.body.scrollHeight);
}
function up(e) {
active = false;
console.log("up")
window.scrollTo(0,document.body.scrollHeight);
}
function move(e) {
if (active) {
if ((Date.now() - actionTimeStamp > 500) && (!actionTimeout)) { // get time elapsed and compare to threshold (500ms)
actionTimeout = true; //this is for the if statement above to prevent multiple timeouts
actionLock = false; // set the lock
setTimeout(function() { // remove lock after 50ms
actionTimeout = false;
actionLock = true;
actionTimeStamp = Date.now(); // timestamp here to make sure we don't lock again to soon. (helps if setTimeout is => than threshold.
}, 50);
}
if (actionLock) { //do our action
console.log("move")
window.scrollTo(0,document.body.scrollHeight);
actionTimeStamp = Date.now(); // timestamp last execution
}
}
}
Thanks to everyone for chipping in with comments and answers. Really appreciated.

Answer:
There are a few things to adjust in your code:
Instead of continuously reassigning delay with a new Timeout Timer, simply use an Interval.
You should only set the Timer if the state is active AND delay does not exist already. this stops multiple Timers from existing
There are a few things to adjust and understand about Timers in JavaScript:
When you set a Timer, the variable that houses the Timer is set to return an Integer. This is the ID of the Timer in the current scope.
When you clear a Timer, the variable isn't reset to undefined - it stays the same Integer/ID. This is because you're not clearing the variable, the scope is stopping the Timer that matches the ID the variable houses.
Because of the above you have to explicitly set the variable housing the Timer to undefined (or some other falsy value) after clearing it for an existence check to work.
var active = false;
var delay;
window.addEventListener("mousedown", down, false);
window.addEventListener("mouseup", up, false);
window.addEventListener("mousemove", move, false);
function down(e) {
active = true;
console.log("down")
window.scrollTo(0,document.body.scrollHeight);
}
function up(e) {
active = false;
clearTimeout(delay); //expecting this to clear delay
delay = undefined;
console.log("up")
window.scrollTo(0,document.body.scrollHeight);
}
function move(e) {
if (active) {
if(!delay) {
delay = setInterval(function() {
console.log("move")
window.scrollTo(0,document.body.scrollHeight);
}, 50);
}
}
else { //fallback in case of Browser Queuing issues
if(delay) {
clearTimeout(delay);
delay = undefined;
}
}
}
Edited
Due to comments with issues I added a fallback in mousemove that will remove the timer if the state is inactive, but delay is still defined. I don't believe that you technically should need this, but in practice Browser Event Queuing and Timers occasionally don't get along as expected.

endless while loop after mousemove

I am going crazy here.
I want to show an element on mouse move, and hide it 10 sec after last move of the mouse.
I wrote this:
document.addEventListener("DOMContentLoaded", function(event) {
var time = 0;
document.addEventListener("mousemove", function(event) {
console.log('$');
document.getElementsByClassName("mybar")[0].style.visibility = 'visible';
time = 0;
while (time < 11) {
setTimeout(function() {
time++
}, 1000);
console.log(time, time == 10);
if (time == 10) {
document.getElementsByClassName("mybar")[0].style.visibility = 'hidden';
}
}
});
});
<div class='mybar'>
<h1> TESTING </h1>
</div>
Why does it end up in an endless loop?
Why doesn't it exit on condition? why does the if never gets the 'true' parameter?
Notice : don't run it this way... it will kill your tab.

First, you don't need to wait for DOMContentLoaded to add an event listener to document, since if you did, you couldn't add DOMContentLoaded in the first place.
The infinite loop is because setTimeout doesn't pause the script. It schedules its callback for the time you provide, and irrespective of that time, the callbacks will not run until the current running code in the thread completes, which never happens because you don't increment the time variable.
So the loop never ends, and so the thread is never made available, so your callbacks never can run, so time can never be incremented.
Lastly, starting a setTimeout inside an event handler that shares a local variable and executes very rapidly on an event like mousemove is prone to give unexpected results. For example, in your code, every time the handler runs, it'll reset time to 0, which doesn't seem to be what you'd want.
A solution would be to ditch the loop, schedule the visibility for 10 seconds, and prevent the main part of the code in the handler from running in the meantime by using a boolean variable.
var timer = null;
document.addEventListener("mousemove", function(event) {
var myBar = document.querySelector(".mybar");
if (!myBar) {
return; // there's no mybar element
}
if (timer == null) {
myBar.style.visibility = 'visible';
} else {
clearTimeout(timer); // clear the currently running timer
}
// set to hidden in 10 seconds
timer = setTimeout(function() {
myBar.style.visibility = 'hidden';
timer = null; // clear the timer
}, 10000);
});
I also switched to querySelector instead of getElementsByClassName because it's shorter and cleaner. And I used a variable to make sure the element is found before setting the style.

You need a flag out of the mousemove scope that tells your listener that you've already ran.
if(running) return;
running = true;
In context:
document.addEventListener("DOMContentLoaded", function(event) {
var time = 0;
var running = false;
document.addEventListener("mousemove", function(event) {
console.log('$');
if(running) return;
running = true;
document.getElementsByClassName("mybar")[0].style.visibility = 'visible';
time = 0;
while (time < 11) {
setTimeout(function() {
time++
}, 1000);
console.log(time, time == 10);
if (time == 10) {
document.getElementsByClassName("mybar")[0].style.visibility = 'hidden';
}
}
});
});

Here's a way to do it with regular JavaScript. If your browser isnt ES6 compliant, you can replace the arrow functions with regular function expressions. The example hides the text after 2 seconds instead of 10, just so you can see it work without having to waste 8 extra seconds.
//hide by default
document.getElementById('myBar').style.display = 'none';
var timer = null;
var hideDivTimer = () => {
timer = setTimeout(() => {
document.getElementById('myBar').style.display = 'none';
}, 2000);
};
document.addEventListener('mousemove', () => {
clearTimeout(timer);
document.getElementById('myBar').style.display = 'inline';
hideDivTimer();
});
<body>
<div id='myBar'>
<h1> TESTING </h1>
</div>
</body>

use onmousemove to reset setTimeout() to start over again（・・？

when mouse moves, the timer function cancelled =="
but i actually want it to count from the beginning instead.
function w()
{
if (parent.C.location == "http://119.247.250.128/wasyoku/home/prime.html")
{ parent.C.location = "weather.html";
wTout = setTimeout(function(){ parent.C.location = "prime.html"; }, wT);
}
else { parent.C.location = "prime.html"; clearTimeout(wTout); }
}
document.onmousemove.clearTimeout(wTout);
do i really need to setTimeout again（・・？
wTout = setTimeout(function(){ parent.C.location = "prime.html"; }, wT);

Yes, if you clear the timeout you have to set it again.
Another thing you can do is set a variable as the last time you moved the mouse and on the ontimeout you can set another settimeout if you moved the mouse in XX seconds

var sto = null;
function myTimeout() {
window.clearTimeout(sto);
sto = setTimeout(function() {
console.log("setTimeout's working");
}, 2000);
}
someElement.addEventListener('mousemove', function() {
myTimeout();
});
jsfiddle DEMO

After setTimeout() check if still mouse out

I have a piece of code that hides an element on mouseout.
The code looks like this:
var myMouseOutFunction = function (event) {
setTimeout(function () {
$(".classToHide").hide();
$(".classToShow").show();
}, 200);
};
This produces a result very close to what I want to do. However, I want to wait the time on the timeout (in this case 200 ms) then check to see if my mouse is still "out" of the element. If it is, I want to do .hide() and .show() on the desired elements.
I want to do this because if a user slightly mouses out then quickly mouses back in, I don't want the elements to flicker (meaning: hide then show real quick) when the user just wants to see the element.

Assign the timeout's return value to a variable, then use clearTimeout in the onmouseover event.

Detailing Kolink answer
DEMO: http://jsfiddle.net/EpMQ2/1/
var timer = null;
element.onmouseout = function () {
timer = setTimeout(function () {
$(".classToHide").hide();
$(".classToShow").show();
}, 200);
}
element.onmouseover = function () {
clearTimeout(timer);
}

You should use mouseenter and mouseleave of jquery. mouseenter and mouseleave will get called only once.and use a flag if to check if mouseenter again called.
var isMouseEnter ;
var mouseLeaveFunction = function (event) {
isMouseEnter = false;
setTimeout(function () {
if(isMouseEnter ){ return;}
$(".classToHide").hide();
$(".classToShow").show();
}, 200);
};
var mouseEnterFunction = function(){
isMouseEnter = true;
}

Use a boolean flag:
var mustWait = true;
var myMouseOutFunction = function (event) {
setTimeout(function () {
if(mustWait){
mustWait = false;
}
else{
$(".classToHide").hide();
$(".classToShow").show();
mustWait = true;
}
}, 200);
};

restart loop after it's paused by flag

I'm putting together some code to essentially replace the contents of a div when I mouseover a specific link. I then added the changer function to cycle through the content replacement automatically. I set flags for mouseover and mouseout and I can actually get the changer function to stop on mouseover but I can't quite figure out how to make it start up again on mouseout. Any advice is appreciated.
var pause=false;
$('.banner-nav a').mouseover(function () {
pause=true;
setFeature(this);
return false;
});
$('.banner-nav a').mouseout(function () {
pause=false;
});
changer(0, 5000);
function setFeature(f) {
var m = $(f).attr('rel');
$('.banner-nav a').not(f).removeClass('active');
$(f).addClass('active');
$('#featureContainer').html($(m).html());
}
function changer(index, interval) {
var buttons = $('.trigger'),
buttons_length = buttons.length;
var button = buttons.eq(index % buttons_length);
setFeature($(button));
setTimeout(function() {
if (!pause) {
changer(++index, interval);
}
}, interval)
}

The issue is that changer is responsible for its own delayed execution, but pausing it stops the scheduled execution. Another problem is that the next scheduled execution (if any) still happens after pausing.
Use setInterval instead of setTimeout. Instead of using a flag, clear the interval to pause and start it again to unpause.
(function() {
var index=0;
function changer() {
var buttons = $('.trigger'),
buttons_length = buttons.length;
var button = buttons.eq(index % buttons_length);
setFeature($(button));
++index;
}
var changerInterval,
period = 5000;
function startChanger() {
if (! changerInterval) {
changerInterval = setInterval(changer, interval);
}
}
function stopChanger() {
clearInterval(changerInterval);
changerInterval = 0;
}
$('.banner-nav a').mouseover(function () {
stopChanger();
setFeature(this);
return false;
});
$('.banner-nav a').mouseout(function () {
startChanger();
});
/* could implement other functions to e.g. change the period */
function setChangerPeriod() {
...
}
window.setChangerPeriod = setChangerPeriod;
...
})