Develop Reference

Stop/interrupt function execution which works with getTime

When I press middle mouse button it shows "after 1 sec" in console after one second. It's ok, it's what I need. But I also want to stop 1 sec delay if I release middle mouse button (mouseup listener). But now while 'wait' function executes 'mouseup' listener of course will not change 'delay' variable to false (only after 1 sec was passed). But mb is there any way I can do it? (to stop 'wait' function, e.g. when it delayed 0.5 sec on mouseup middle button, not 1 sec)
function wait(ms){
var start = new Date().getTime();
var end = start;
while((end < start + ms) && delay == true) {
end = new Date().getTime();
}
}
var delay = false;
document.addEventListener("mousedown", function(e) {
if (e.button == 1) { // 1 - middle mouse button
delay = true;
wait(1000); // delay 1 sec
console.log("after 1 sec");
}
});
document.addEventListener("mouseup", function(e) {
if (e.button == 1) {
delay = false;
}
});
update:
I'm going to replace console.log("after 1 sec"); with document.execCommand("copy");, We can delay copy to clipboard maximum for 1 sec in Chrome browser using setTimeout() func, but it won't work in Firefox with setTimeout(), but wait(999); document.execCommand('copy'); works for Firefox (999 ms maximum allowed)

Your problem is that the mousedown listener function will block further execution until it finishes. Your wait function implements so called "busy waiting". You should use setTimeout() which allows you to execute a function asynchronously after a specific time. You get a handle back from setTimeout() which you can use to abort the timeout if you release the mouse button. See https://developer.mozilla.org/en/docs/Web/API/WindowTimers/setTimeout for more information.

javascript increment setInteval counter while video is playing

I have the following code that detect if user is idle or not. On page load, a timer will run and if the user is idle for a certain of seconds the timer will pause and resume if the user is active. And I have also codes that detect if video is playing, if the video is playing timer should run and if the video is stop/pause a timeout will run and detect if the user is still active
The problem is even if video is playing, the timer paused and it will start to idle. What I want is when video is playing timer should countinue to increment.
Heres my code:
function setPlayingVideoToTrue(){playing_video = true;}
function setPlayingVideoToFalse(){playing_video = false;}
// check if a video iframe exists
var iframe_videos = $('body').find('iframe');
if(iframe_videos.length > 0){
// create ready events for every iframe
iframe_videos.each(function(index){
// add a temporary id for the iframe
// append additional parameters to the end of the iframe's src
var temporary_player_id = 'iframe_player_'+ index;
var new_iframe_src = $(this).attr('src') +'?api=1&player_id='+ temporary_player_id;
$(this).attr('id', temporary_player_id);
$(this).attr('src', new_iframe_src);
// add event listener for ready
$f(this).addEvent('ready', iframe_ready);
});
// when a player is ready, add event listeners for play, pause, finish, and playProgress
function iframe_ready(player_id) {
$f(player_id).addEvent('play', setPlayingVideoToTrue);
$f(player_id).addEvent('playProgress', setPlayingVideoToTrue);
$f(player_id).addEvent('pause', setPlayingVideoToFalse);
$f(player_id).addEvent('finish', setPlayingVideoToFalse);
}
}
function start_idle_timer(){
var timer = 0;
function increment_duration()
{
if(isPaused === false)
{
timer++;
}
// increment timer if video is playing
if(playing_video === true){
clearTimeout(idleTimer);
isPaused = false;
}
if(playing_video === false && isPaused === false){
// stop timer if the user is idle for 3 minutes
var idleTimer = setTimeout(function(){
// console.log('idle');
clearInterval(check_time);
isPaused = true;
// a modal will apper to inform that user is on idle state
$('#linkage').trigger('click');
var modal_timer = 0;
// timer for modal idle timer
continue_modal_timer = setInterval(function(){
modal_timer++;
inactivity_timer = modal_timer;
if(modal_timer == 60)
{
clearInterval(continue_modal_timer);
clearTimeout(idleTimer);
}
}, 1000)
}, 10000);
}
// bind to all elements on DOM possible events indicating the user is active
$('*').bind('mousemove click mouseup mousedown keydown keypress keyup submit change mouseenter scroll resize dblclick', function () {
clearTimeout(idleTimer);
isPaused = false;
});
}
// initialize the interval
check_time = setInterval(increment_duration, 1000);
}
// check if start_timer is present from the loading page to record the time duration of the user
if($('.start_timer').length > 0){
start_idle_timer();
}

Run setTimeout only when tab is active

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);
})();

How to automatically reload a page after a given period of inactivity

How can I automatically reload a webpage, if there have been no activity on the page for a given period of time?

This can be accomplished without javascript, with this metatag:
<meta http-equiv="refresh" content="5" >
where content ="5" are the seconds that the page will wait until refreshed.
But you said only if there was no activity, what kind for activity would that be?

If you want to refresh the page if there is no activity then you need to figure out how to define activity. Let's say we refresh the page every minute unless someone presses a key or moves the mouse. This uses jQuery for event binding:
<script>
var time = new Date().getTime();
$(document.body).bind("mousemove keypress", function(e) {
time = new Date().getTime();
});
function refresh() {
if(new Date().getTime() - time >= 60000)
window.location.reload(true);
else
setTimeout(refresh, 10000);
}
setTimeout(refresh, 10000);
</script>

I have built a complete javascript solution as well that does not require jquery. Might be able to turn it into a plugin. I use it for fluid auto-refreshing, but it looks like it could help you here.
JSFiddle AutoRefresh
// Refresh Rate is how often you want to refresh the page
// bassed off the user inactivity.
var refresh_rate = 200; //<-- In seconds, change to your needs
var last_user_action = 0;
var has_focus = false;
var lost_focus_count = 0;
// If the user loses focus on the browser to many times
// we want to refresh anyway even if they are typing.
// This is so we don't get the browser locked into
// a state where the refresh never happens.
var focus_margin = 10;
// Reset the Timer on users last action
function reset() {
last_user_action = 0;
console.log("Reset");
}
function windowHasFocus() {
has_focus = true;
}
function windowLostFocus() {
has_focus = false;
lost_focus_count++;
console.log(lost_focus_count + " <~ Lost Focus");
}
// Count Down that executes ever second
setInterval(function () {
last_user_action++;
refreshCheck();
}, 1000);
// The code that checks if the window needs to reload
function refreshCheck() {
var focus = window.onfocus;
if ((last_user_action >= refresh_rate && !has_focus && document.readyState == "complete") || lost_focus_count > focus_margin) {
window.location.reload(); // If this is called no reset is needed
reset(); // We want to reset just to make sure the location reload is not called.
}
}
window.addEventListener("focus", windowHasFocus, false);
window.addEventListener("blur", windowLostFocus, false);
window.addEventListener("click", reset, false);
window.addEventListener("mousemove", reset, false);
window.addEventListener("keypress", reset, false);
window.addEventListener("scroll", reset, false);
document.addEventListener("touchMove", reset, false);
document.addEventListener("touchEnd", reset, false);

<script type="text/javascript">
var timeout = setTimeout("location.reload(true);",600000);
function resetTimeout() {
clearTimeout(timeout);
timeout = setTimeout("location.reload(true);",600000);
}
</script>
Above will refresh the page every 10 minutes unless resetTimeout() is called. For example:
clicky

Based on the accepted answer of arturnt. This is a slightly optimized version, but does essentially the same thing:
var time = new Date().getTime();
$(document.body).bind("mousemove keypress", function () {
time = new Date().getTime();
});
setInterval(function() {
if (new Date().getTime() - time >= 60000) {
window.location.reload(true);
}
}, 1000);
Only difference is that this version uses setInterval instead of setTimeout, which makes the code more compact.

var bd = document.getElementsByTagName('body')[0];
var time = new Date().getTime();
bd.onmousemove = goLoad;
function goLoad() {
if(new Date().getTime() - time >= 1200000) {
time = new Date().getTime();
window.location.reload(true);
}else{
time = new Date().getTime();
}
}
Each time you move the mouse it will check the last time you moved the mouse. If the time interval is greater than 20' it will reload the page, else it will renew the last-time-you-moved-the-mouse.

use JavaScript setInterval method:
setInterval(function(){ location.reload(); }, 3000);

Auto reload with target of your choice. In this case target is _self set to itself,but you could change the reload page by simply changing the window.open('self.location', '_self'); code to something like this examplewindow.top.location="window.open('http://www.YourPageAdress.com', '_self'";.
With a confirmation ALERT message:
<script language="JavaScript">
function set_interval() {
//the interval 'timer' is set as soon as the page loads
var timeoutMins = 1000 * 1 * 15; // 15 seconds
var timeout1Mins = 1000 * 1 * 13; // 13 seconds
itimer=setInterval("auto_logout()",timeoutMins);
atimer=setInterval("alert_idle()",timeout1Mins);
}
function reset_interval() {
var timeoutMins = 1000 * 1 * 15; // 15 seconds
var timeout1Mins = 1000 * 1 * 13; // 13 seconds
//resets the timer. The timer is reset on each of the below events:
// 1. mousemove 2. mouseclick 3. key press 4. scrolling
//first step: clear the existing timer
clearInterval(itimer);
clearInterval(atimer);
//second step: implement the timer again
itimer=setInterval("auto_logout()",timeoutMins);
atimer=setInterval("alert_idle()",timeout1Mins);
}
function alert_idle() {
var answer = confirm("Session About To Timeout\n\n You will be automatically logged out.\n Confirm to remain logged in.")
if (answer){
reset_interval();
}
else{
auto_logout();
}
}
function auto_logout() {
//this function will redirect the user to the logout script
window.open('self.location', '_self');
}
</script>
Without confirmation alert:
<script language="JavaScript">
function set_interval() {
//the interval 'timer' is set as soon as the page loads
var timeoutMins = 1000 * 1 * 15; // 15 seconds
var timeout1Mins = 1000 * 1 * 13; // 13 seconds
itimer=setInterval("auto_logout()",timeoutMins);
}
function reset_interval() {
var timeoutMins = 1000 * 1 * 15; // 15 seconds
var timeout1Mins = 1000 * 1 * 13; // 13 seconds
//resets the timer. The timer is reset on each of the below events:
// 1. mousemove 2. mouseclick 3. key press 4. scrolling
//first step: clear the existing timer
clearInterval(itimer);
clearInterval(atimer);
//second step: implement the timer again
itimer=setInterval("auto_logout()",timeoutMins);
}
function auto_logout() {
//this function will redirect the user to the logout script
window.open('self.location', '_self');
}
</script>
Body code is the SAME for both solutions:
<body onLoad="set_interval(); document.form1.exp_dat.focus();" onKeyPress="reset_interval();" onmousemove="reset_interval();" onclick="reset_interval();" onscroll="reset_interval();">

I came up with a slightly different solution, because I found that setInterval isn't really accurate, see: setInterval timing slowly drifts away from staying accurate
// Based on https://stackoverflow.com/a/15279599
// Refresh Rate is how often you want to refresh the page
// based off the user inactivity (in seconds).
var refresh_after = 20;
var last_user_action = new Date();
// Reset the Timer on users last action
function reset() {
last_user_action = new Date();
}
// Countdown that executes every second.
setInterval(function () {
refreshCheck();
}, 1000);
// The code that checks if the window needs to reload
function refreshCheck() {
var expire_time = new Date(last_user_action);
expire_time.setSeconds(expire_time.getSeconds() + refresh_after);
now = new Date();
if (now.getTime() >= expire_time.getTime() && document.readyState == "complete") {
window.location.href = window.location.href; // We do this to discard the POST data.
}
}
window.addEventListener("click", reset, false);
window.addEventListener("mousemove", reset, false);
window.addEventListener("keypress", reset, false);
window.addEventListener("scroll", reset, false);
document.addEventListener("touchMove", reset, false);
document.addEventListener("touchEnd", reset, false);

Yes dear,then you have to use Ajax technology. to changes contents of
particular html tag:
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<title>Ajax Page</title>
<script>
setInterval(function () { autoloadpage(); }, 30000); // it will call the function autoload() after each 30 seconds.
function autoloadpage() {
$.ajax({
url: "URL of the destination page",
type: "POST",
success: function(data) {
$("div#wrapper").html(data); // here the wrapper is main div
}
});
}
</script>
</head>
<body>
<div id="wrapper">
contents will be changed automatically.
</div>
</body>
</html>

I would consider activity to be whether or not the user is focused on the window. For example, when you click from one window to another (e.g. Google Chrome to iTunes, or Tab 1 to Tab 2 within an internet browser), the webpage can send a callback saying "Im out of focus!" or "Im in focus!". One could use jQuery to harness this possible lack of activity to do whatever they wanted. If I were in your position, I would use the following code to check for focus every 5 seconds, etc and reload if no focus.
var window_focus;
$(window).focus(function() {
window_focus = true;
}).blur(function() {
window_focus = false;
});
function checkReload(){
if(!window_focus){
location.reload(); // if not focused, reload
}
}
setInterval(checkReload, 5000); // check if not focused, every 5 seconds

And finally the most simple solution:
With alert confirmation:
<script type="text/javascript">
// Set timeout variables.
var timoutWarning = 3000; // Display warning in 1Mins.
var timoutNow = 4000; // Timeout in 2 mins.
var warningTimer;
var timeoutTimer;
// Start timers.
function StartTimers() {
warningTimer = setTimeout("IdleWarning()", timoutWarning);
timeoutTimer = setTimeout("IdleTimeout()", timoutNow);
}
// Reset timers.
function ResetTimers() {
clearTimeout(warningTimer);
clearTimeout(timeoutTimer);
StartTimers();
$("#timeout").dialog('close');
}
// Show idle timeout warning dialog.
function IdleWarning() {
var answer = confirm("Session About To Timeout\n\n You will be automatically logged out.\n Confirm to remain logged in.")
if (answer){
ResetTimers();
}
else{
IdleTimeout();
}
}
// Logout the user and auto reload or use this window.open('http://www.YourPageAdress.com', '_self'); to auto load a page.
function IdleTimeout() {
window.open(self.location,'_top');
}
</script>
Without alert confirmation:
<script type="text/javascript">
// Set timeout variables.
var timoutWarning = 3000; // Display warning in 1Mins.
var timoutNow = 4000; // Timeout in 2 mins.
var warningTimer;
var timeoutTimer;
// Start timers.
function StartTimers() {
warningTimer = setTimeout(timoutWarning);
timeoutTimer = setTimeout("IdleTimeout()", timoutNow);
}
// Reset timers.
function ResetTimers() {
clearTimeout(warningTimer);
clearTimeout(timeoutTimer);
StartTimers();
$("#timeout").dialog('close');
}
// Logout the user and auto reload or use this window.open('http://www.YourPageAdress.com', '_self'); to auto load a page.
function IdleTimeout() {
window.open(self.location,'_top');
}
</script>
Body code is the SAME for both solutions
<body onload="StartTimers();" onmousemove="ResetTimers();" onKeyPress="ResetTimers();">

With on page confirmation text instead of alert
Since this is another method to auto load if inactive I give it a second answer. This one is more simple and easier to understand.
With reload confirmation on the page
<script language="javaScript" type="text/javascript">
<!--
var autoCloseTimer;
var timeoutObject;
var timePeriod = 5100; // 5,1 seconds
var warnPeriod = 5000; // 5 seconds
// Warning period should always be a bit shorter then time period
function promptForClose() {
autoCloseDiv.style.display = 'block';
autoCloseTimer = setTimeout("definitelyClose()", warnPeriod);
}
function autoClose() {
autoCloseDiv.style.display = 'block'; //shows message on page
autoCloseTimer = setTimeout("definitelyClose()", timePeriod); //starts countdown to closure
}
function cancelClose() {
clearTimeout(autoCloseTimer); //stops auto-close timer
autoCloseDiv.style.display = 'none'; //hides message
}
function resetTimeout() {
clearTimeout(timeoutObject); //stops timer
timeoutObject = setTimeout("promptForClose()", timePeriod); //restarts timer from 0
}
function definitelyClose() {
// If you use want targeted reload: parent.Iframe0.location.href = "https://URLHERE.com/"
// or this: window.open('http://www.YourPageAdress.com', '_self');
// of for the same page reload use: window.top.location=self.location;
// or window.open(self.location;, '_self');
window.top.location=self.location;
}
-->
</script>
Confirmation box when using with on page confirmation
<div class="leftcolNon">
<div id='autoCloseDiv' style="display:none">
<center>
<b>Inactivity warning!</b><br />
This page will Reloads automatically unless you hit 'Cancel.'</p>
<input type='button' value='Load' onclick='definitelyClose();' />
<input type='button' value='Cancel' onclick='cancelClose();' />
</center>
</div>
</div>
Body codes for both are the SAME
<body onmousedown="resetTimeout();" onmouseup="resetTimeout();" onmousemove="resetTimeout();" onkeydown="resetTimeout();" onload="timeoutObject=setTimeout('promptForClose()',timePeriod);">
NOTE: If you do not want to have the on page confirmation, use Without confirmation
<script language="javaScript" type="text/javascript">
<!--
var autoCloseTimer;
var timeoutObject;
var timePeriod = 5000; // 5 seconds
function resetTimeout() {
clearTimeout(timeoutObject); //stops timer
timeoutObject = setTimeout("definitelyClose()", timePeriod); //restarts timer from 0
}
function definitelyClose() {
// If you use want targeted reload: parent.Iframe0.location.href = "https://URLHERE.com/"
// or this: window.open('http://www.YourPageAdress.com', '_self');
// of for the same page reload use: window.top.location=self.location;
// or window.open(self.location;, '_self');
window.top.location=self.location;
}
-->
</script>

Using LocalStorage to keep track of the last time of activity, we can write the reload function as follows
function reloadPage(expiryDurationMins) {
const lastInteraction = window.localStorage.getItem('lastinteraction')
if (!lastInteraction) return // no interaction recorded since page load
const inactiveDurationMins = (Date.now() - Number(lastInteraction)) / 60000
const pageExpired = inactiveDurationMins >= expiryDurationMins
if (pageExpired) window.location.reload()
}
Then we create an arrow function which saves the last time of interaction in milliseconds(String)
const saveLastInteraction = () => window.localStorage.setItem('last', Date.now().toString())
We will need to listen to the beforeunload event in the browser to clear our lastinteraction record so we don't get stuck in an infinite reload loop.
window.addEventListener('beforeunload', () => window.localStorage.removeItem('lastinteraction'))
The user activity events we will need to monitor would be mousemove and keypress. We store the last interaction time when the user moves the mouse or presses a key on the keyboard
window.addEventListener('mousemove', saveLastInteraction)
window.addEventListener('keypress', saveLastInteraction)
To set up our final listener, we will use the load event.
On page load, we use the setInterval function to check if the page has expired after a certain period.
const expiryDurationMins = 1
window.addEventListener('load', setInterval.bind(null, reloadPage.bind(null, expiryDurationMins), 1000))

I am doing it like this:
let lastActionTaken = new Date().getTime();
function checkLastAction() {
let now = new Date().getTime();
if (now - lastActionTaken > 1000 * 60 * 60) window.location.reload();
else lastActionTaken = now;
}
window.addEventListener("mousemove", checkLastAction);
window.addEventListener("touchstart", checkLastAction);
window.addEventListener("keydown", checkLastAction);
This will reload the page as soon as the user moves their mouse, hits a key or touches a touchscreen if it has been inactive for 1 hour. Also, this takes care of the focus as well, so if a user is moving their mouse in a different program and then come back to this window it will reload, which is good because the point is to not have old data being shown.

Many of these other answers either don't answer the main part of the question "with no activity", or they are incredibly, unnecessarily complex. I have taken the accepted answer (here: https://stackoverflow.com/a/4644315/9008140 )
and modified it to take advantage of the fact you can assign timers to variables. This allows us to get rid of the second timer, as well as the timestamp.
/**
* create a timer that refreshes the page after the number of
minutes has passed without user interaction.
* Moving the mouse or pressing a key on the current page will start
the timer over.
* #param {any} minutes
*/
var refreshTimer;
function setPageRefreshTimer(minutes) {
var refreshInterval = minutes * 60 * 1000; //interval is in milliseconds. We refresh every x minutes.
$(document.body).bind("mousemove keypress", function (e) {
if (refreshTimer != null && refreshTimer != undefined) {
window.clearTimeout(refreshTimer);
}
refreshTimer = window.setTimeout(function () { window.location.reload(true); }, refreshInterval);
});
refreshTimer = window.setTimeout(function () { window.location.reload(true); }, refreshInterval);
}
This sample code will refresh based on a passed in parameter in minutes, with an accuracy as great as a javascript timer can be. In testing, always less than a second. I created this as a function but you can pull it into your page if you wish.

This task is very easy use following code in html header section
<head> <meta http-equiv="refresh" content="30" /> </head>
It will refresh your page after 30 seconds.

How can I execute a setTimeout() only when the user is present (with the mouse movement) with jQuery

I have a function that updates a <div /> via AJAX:
function update() {
<!-- .ajax() -->
setTimeout(update(), 3000);}
}
What I need is that this is not executed when the user is not present on the website, so if there is no movement of the mouse (we will suppose that if move it is in the website) it will not update .mousemove(). By the way, there is any other thing that we can do to know is someone is active on the website?
How can this be done? Thank you in advance!
Edit: probably I explained bad. I need to know the way to only update when there is activity. Like Facebook does with his news feed, the front page. Thanks!

You could use a mousemove handler to track when the user last moved, and then have the process only happen if they last moved the mouse within X seconds. But of course, if the user is sitting there reading something, or if they're a keyboard-oriented kind of person, that will tend to miss that they are there... So you'd probably want to look at keydown as well.
Here's a mousemove example:
jQuery(function($) {
var count = 0, lastmove = new Date();
$(document).mousemove(function() {
++count;
lastmove = new Date();
$('#display').html("Moved " + count + " times");
});
});​
Then your update code could do this:
function update() {
if (new Date() - lastmove < 60000) { // 60 seconds
// Really do the update
}
else {
// Check back in a few seconds
setTimeout(update, 3000);
}
}
Off-topic, but you have an error in your update code. You have:
setTimeout(update(), 3000);
...which will call update immediately and then try to use its return value to schedule something to happen in three seconds. If you want the call to update to be scheduled to happen in three seconds, leave off the () after it:
setTimeout(update, 3000);

I think I might have ended up with something such as this. Avoids date arithmetic. Only cares whether there's been some activity since the last update().
window.activeFlag = false;
window.updateDelay = 3000;
$(document).bind('mousemove scroll keydown', function(){ activeFlag = true; });
function update() {
if(activeFlag) {
doWork();
activeFlag = false;
}
}
window.setTimeout(update, updateDelay);
edit: I've discovered a flaw in the code. The following is more appropriate:
window.activeFlag = false;
window.updateDelay = 3000;
$(document).bind('mousemove scroll keydown', function(){ activeFlag = true; });
function update() {
if(activeFlag) {
doWork();
activeFlag = false;
}
window.setTimeout(update, updateDelay);
}
update();

I think there is no easy way to determine if the user is present
I would use a combination of mousemove, scroll, keypress.

var bUpdate = false;
function update() {
if(bUpdate){
///perform your ajax request
}
}
$(document).mousemove(function(){
bUpdate = true;
setTimeout(function(){bUpdate=false;}, 3000);}
});