How to detect idle time in JavaScript elegantly?

Question

Is it possible to detect \"idle\" time in JavaScript?
My primary use case probably would be to pre-fetch or preload content.

Idle time:

Answer 1

Here is the best solution I have found: http://css-tricks.com/snippets/jquery/fire-event-when-user-is-idle/

Here is the JS:

idleTimer = null;
idleState = false;
idleWait = 2000;

(function ($) {

    $(document).ready(function () {

        $('*').bind('mousemove keydown scroll', function () {

            clearTimeout(idleTimer);

            if (idleState == true) { 

                // Reactivated event
                $("body").append("<p>Welcome Back.</p>");            
            }

            idleState = false;

            idleTimer = setTimeout(function () { 

                // Idle Event
                $("body").append("<p>You've been idle for " + idleWait/1000 + " seconds.</p>");

                idleState = true; }, idleWait);
        });

        $("body").trigger("mousemove");

    });
}) (jQuery)

Answer 2

Improving on Equiman's (original) answer:

function idleLogout() {
    var t;
    window.onload = resetTimer;
    window.onmousemove = resetTimer;
    window.onmousedown = resetTimer;  // catches touchscreen presses as well      
    window.ontouchstart = resetTimer; // catches touchscreen swipes as well 
    window.onclick = resetTimer;      // catches touchpad clicks as well
    window.onkeydown = resetTimer;   
    window.addEventListener('scroll', resetTimer, true); // improved; see comments

    function yourFunction() {
        // your function for too long inactivity goes here
        // e.g. window.location.href = 'logout.php';
    }

    function resetTimer() {
        clearTimeout(t);
        t = setTimeout(yourFunction, 10000);  // time is in milliseconds
    }
}
idleLogout();

.
Apart from the improvements regarding activity detection, and the change from document to window, this script actually calls the function, rather than letting it sit idle by.

It doesn't catch zero CPU usage directly, but that is impossible, because executing a function causes CPU usage. And user inactivity eventually leads to zero CPU usage, so indirectly it does catch zero CPU usage.

Answer 3

You could probably detect inactivity on your web page using the mousemove tricks listed, but that won't tell you that the user isn't on another page in another window or tab, or that the user is in Word or Photoshop, or WOW and just isn't looking at your page at this time. Generally I'd just do the prefetch and rely on the client's multi-tasking. If you really need this functionality you do something with an activex control in windows, but it's ugly at best.

Answer 4

You could probably hack something together by detecting mouse movement on the body of the form and updating a global variable with the last movement time. You'd then need to have an interval timer running that periodically checks the last movement time and does something if it has been sufficiently long since the last mouse movement was detected.

Answer 5

I wrote a small ES6 class to detect activity and otherwise fire events on idle timeout. It covers keyboard, mouse and touch, can be activated and deactivated and has a very lean API:

const timer = new IdleTimer(() => alert('idle for 1 minute'), 1000 * 60 * 1);
timer.activate();

It does not depend on jQuery, though you might need to run it through Babel to support older browsers.

https://gist.github.com/4547ef5718fd2d31e5cdcafef0208096

I might release it as an npm package once I get some feedback.

Answer 6

Pure JavaScript with properly set reset time and bindings via addEventListener

(function() {

  var t,
    timeout = 5000;

  function resetTimer() {
    console.log("reset: " + new Date().toLocaleString());
    if (t) { 
      window.clearTimeout(t); 
    }
    t = window.setTimeout(logout, timeout);
  }

  function logout() {
    console.log("done: " + new Date().toLocaleString());
  }
  resetTimer();

  //And bind the events to call `resetTimer()`
  ["click", "mousemove", "keypress"].forEach(function(name) {
    console.log(name);
    document.addEventListener(name, resetTimer);
  });

}());