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need to set a timer for in javascript , then clear

I want to create a timer in JavaScript. I see the setTimeout(fn, 100) but unclear how to wrap this so it will clear itself at the end.
I tried doing
var buttonTimer = null;
$scope.backButton = function() {
if(buttonTimer === null){
$history.back();
}
buttonTimer = setTimeout(function(buttonTimer){
buttonTimer = null;
}, 100);
}
The whole point is to prevent the user from hitting this function too quickly.. and ignoring all subsequent clicks within that 100ms window, at the end of the window, clear the timer and resume accepting clicks

Since you are doing angular, I prepared a plnkr for demonstration:
http://plnkr.co/edit/5qrslKpmkglXTvEyYgBr?p=preview
Your code is almost Ok, the only problem is that you start a new timeout on every click. The effect is, that the callback fires multiple times and resets buttonTimer.
So the only change is:
var blocker = null;
$scope.backButton = function() {
if(blocker == null) {
blocker = setTimeout(function(){
blocker = null;
}, 1500);
// DO YOUR STUFF HERE
}
};

You can use throttle from lodash/underscore or Ramdajs.
for example
$scope.backButton=_.throttle(100,function(){/* do something here */});

function is looped according to setinterval but with different parameters

i have a simple question, there is a function with parameter emp_id that opens up a form for a chat with different attributes, i want it to be refreshed automatically each 10 sec, now it works a bit wrongly, since there is a parameter emp_id that is can be changed, and once i change it, the chat with messages and form are refreshed double time or triple times :) depend on how many times u change the emp_id, i hope i was clear )) anyway here is the javascript function:
function load_chat(emp_id) {
var url = "#request.self#?fuseaction=objects2.popup_list_chatform"
url = url + "&employee_id=" + emp_id;
document.getElementById('form_div').style.display = 'block'; AjaxPageLoad(url,'form_div',1,'Yükleniyor');
setInterval( function() {
load_chat(emp_id);
},10000);
}
there a list of names, once i click on one of them, this form is opened by this function, but if i click another user, i mean if i change the emp_id, it refreshes, the previous and present form. how do i change it so that it will refresh only the last emp_id, but not all of id's which i've changed
thank you all for the help, i really appreciate it!

This would nicely encapsulate what you're doing. The timer id (tid) is kept inside the closure, so when you call load_chat it will stop the interval if there was one running.
Once the new url is set up, it will start the interval timer again.
var ChatModule = (function() {
var tid,
url;
function refresh()
{
AjaxPageLoad(url, 'form_div', 1, 'Yükleniyor');
}
return {
load_chat: function(emp_id) {
if (tid) {
clearInterval(tid);
}
// setup url
url = "#request.self#?fuseaction=objects2.popup_list_chatform"
url = url + "&employee_id=" + emp_id;
document.getElementById('form_div').style.display = 'block';
// load ajax
refresh();
// set timer
tid = setInterval(refresh, 10000);
}
}
}());
ChatModule.load_chat(123);

Use setTimeout instead. Each time your function is executed, it will set up the next execution (you could also make it conditional):
function load_chat(emp_id) {
... // do something
if (condition_still_met)
setTimeout(function() {
load_chat(emp_id); // with same id
}, 10000);
}
load_chat("x"); // to start
Or you will have to use setInterval outside the load_chat function. You can clear the interval when necessary.
function get_chat_loader(emp_id) {
return function() {
... // do something
};
}
var id = setInterval(get_chat_loader("x"), 10000); // start
// then, somewhen later:
clearInterval(id);

setTimeout does bizarre things when executing in a tab that doesn't have focus [duplicate]

Is there a way to stop setTimeout("myfunction()",10000); from counting up when the page isn't active. For instance,
A user arrives at a "some page" and stays there for 2000ms
User goes to another tab, leaves "some page" open.
myfunction() doesn't fire until they've come back for another 8000ms.

(function() {
var time = 10000,
delta = 100,
tid;
tid = setInterval(function() {
if ( document.hidden ) { return; }
time -= delta;
if ( time <= 0 ) {
clearInterval(tid);
myFunction(); // time passed - do your work
}
}, delta);
})();
Live demo: https://jsbin.com/xaxodaw/quiet
Changelog:
June 9, 2019: I’ve switched to using document.hidden to detect when the page is not visible.

Great answer by Šime Vidas, it helped me with my own coding. For completeness sake I made an example for if you want to use setTimeout instead of setInterval:
(function() {
function myFunction() {
if(window.blurred) {
setTimeout(myFunction, 100);
return;
}
// What you normally want to happen
setTimeout(myFunction, 10000);
};
setTimeout(myFunction, 10000);
window.onblur = function() {window.blurred = true;};
window.onfocus = function() {window.blurred = false;};
})();
You'll see that the window blurred check has a shorter time set than normal, so you can set this depending on how soon you require the rest of the function to be run when the window regains focus.

You can do something like:
$([window, document]).blur(function() {
// Clear timeout here
}).focus(function() {
// start timeout back up here
});
Window is for IE, document is for the rest of the browser world.

I use almost the same approach as Šime Vidas in my slider
but my code is based on document.visibilityState for page visibility checking:
document.addEventListener("visibilitychange", () => {
if ( document.visibilityState === "visible" ) {
slideshow.play();
} else {
slideshow.pause();
}
});
About Page Visibility
API: https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API

What you'd have to do is set up a mechanism to set timeouts at small intervals, keeping track of total elapsed time. You'd also track "mouseenter" and "mouseleave" on the whole page (the <body> or something). When the short-term timeouts expire, they can check the window state (in or out) and not restart the process when the window is not in focus. The "mouseenter" handler would start all paused timers.
edit — #Šime Vidas has posted an excellent example.

I've finally implemented a variation of #Šime Vidas' answer, because the interval was still running if I opened another program and the browser window was not visible, but the page executing the interval was the active browser tab. So, I've modified the condition to document.hidden || !document.hasFocus(). This way, if the document is hidden or the document doesn't have the focus, the interval function just returns.
(function() {
var time = 10000,
delta = 100,
tid;
tid = setInterval(function() {
if ( document.hidden || !document.hasFocus() ) { return; }
time -= delta;
if ( time <= 0 ) {
clearInterval(tid);
myFunction(); // time passed - do your work
}
}, delta);
})();

javascript avoid multiple call

My problem here is i want to avoid calling a javascript function for a time period(say after 5 sec) after it has been called.
i created a link, which calls the javascript function.and if the user double clicks it is called twice i want to avoid that.
Thanks,
Devan

I think the most sensible way to handle that is to disable the link once it is clicked, and then reenable it when the function is done running. Assuming you have jQuery available, something like...
$('#button').click(function () {
$(this).attr("disabled", "true");
doTheFunction();
$(this).attr("disabled", "false");
});
If you really need to wait a set amount of time after the function is called, then you could use setTimeout to reenable the button.
$('#button').click(function () {
$(this).attr("disabled", "true");
doTheFunction();
var btn = $(this);
setTimeout(function () {
btn.attr("disabled", "false");
}, 5000); // reenable the button 5 seconds later
});
EDIT: (for the comment below)
For a link, I would simulate the above by adding and removing a class, since you're right, there's no disabled attribute.
$('#link').click(function () {
if ($(this).hasClass('disabled_link')) {
return;
}
$(this).addClass("disabled_link");
doTheFunction();
var link = $(this);
setTimeout(function () {
link.removeClass("disabled_link");
}, 5000); // reenable the button 5 seconds later
});

Since you are using a link, not a button, and not jQuery (apparently), here's how to stop a function doing anything for 5 seconds (or whatever delay you want) after it has been called and done something:
var someFn = (function() {
var lastCalled;
return function() {
var now = new Date();
var limit = 5000; // minimum milliseconds between calls
if (!lastCalled || (now - lastCalled) > limit) {
lastCalled = now;
// do stuff
alert('hey');
} else {
return;
}
}
}());
This sort of thing is generally handled at the server though, since client scripts aren't particularly reliable - you can't guarantee that the dealy will be implemented, no matter what strategy you use.

Jquery ajax live validation / timeout question

I'm still kindof new to jQuery, so there probably is an easy solution, but I can't find anything.
I've made this registration form, that checks if the username or email is taken as the user is typing in the username. Basically it just makes a json request that returns true or false depending on if the username / email is already taken.
The problem is, that now it makes a request on basically every keypress that the user makes while focused on the field if the input text is more than 3 characters long. For now, that works, but that's a lot of server requests. I'd like it to make a request only when the user has not typed for, say, a half second.
Any ideas on how I might be able to do that ?
$(document).ready(function() {
$("#user_username").keyup(function () {
var ln = $(this).val().length;
if (ln > 3) {
$.getJSON("/validate/username/",
{value:$(this).val()},
function(data){
if (data.reg == true) {
$("#status-for-username").html("Username already in use");
} else {
$("#status-for-username").html("Username available");
}
});
}
});
$("#user_email").keyup(function () {
var ln = $(this).val().length;
if (ln > 3) {
$.getJSON("/validate/email/",
{value:$(this).val()},
function(data){
if (data.reg == true) {
$("#status-for-email").html("E-mail already in use");
} else {
$("#status-for-email").html("");
}
});
}
});
});

For waiting an amount of time since the last keystroke, you could do something like the jQuery.typeWatch plugin does.
Here I post you a light implementation of the concept:
Usage:
$("#user_username").keyup(function () {
typewatch(function () {
// executed only 500 ms after the last keyup event.
}, 500);
Implementation:
var typewatch = function(){
var timer = 0; // store the timer id
return function(callback, ms){
clearTimeout (timer); // if the function is called before the timeout
timer = setTimeout(callback, ms); // clear the timer and start it over
}
}();
StackOverflow uses the plugin I mention, for syntax coloring the code on edition.

You can use window.setTimeout and window.clearTimeout. Basically trigger a function to invoke in x milliseconds and if another keypress event is fired beforehand then you clear that handler and start a new one.
//timeout var
var timer;
$('#username').keyUp( function(){
//clear any existing timer
window.clearTimeout( timer );
//invoke check password function in 0.5 seconds
timer = window.setTimeout( checkPasswordFunc, 500 );
});
function checkPasswordFunc(){
//ajax call goes here
}