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: Period of user inactivity or without any CPU usage

Answer 1

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 2

Similar to Iconic's solution above (with jQuery custom event)...

// use jquery-idle-detect.js script below
$(window).on('idle:start', function(){
  //start your prefetch etc here...
});

$(window).on('idle:stop', function(){
  //stop your prefetch etc here...
});

---

//jquery-idle-detect.js
(function($,$w){
  // expose configuration option
  // idle is triggered when no events for 2 seconds
  $.idleTimeout = 2000;

  // currently in idle state
  var idle = false;

  // handle to idle timer for detection
  var idleTimer = null;

  //start idle timer and bind events on load (not dom-ready)
  $w.on('load', function(){
    startIdleTimer();
    $w.on('focus resize mousemove keyup', startIdleTimer)
      .on('blur',idleStart) //force idle when in a different tab/window
      ;
  ]);

  function startIdleTimer() {
    clearTimeout(idleTimer); //clear prior timer

    if (idle) $w.trigger('idle:stop'); //if idle, send stop event
    idle = false; //not idle

    var timeout = ~~$.idleTimeout; // option to integer
    if (timeout <= 100) timeout = 100; // min 100ms
    if (timeout > 300000) timeout = 300000; // max 5 minutes

    idleTimer = setTimeout(idleStart, timeout); //new timer
  }

  function idleStart() {
    if (!idle) $w.trigger('idle:start');
    idle = true;
  }

}(window.jQuery, window.jQuery(window)))

Answer 3

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);
  });

}());

Answer 4

Here is an AngularJS service for accomplishing in Angular.

/* Tracks now long a user has been idle.  secondsIdle can be polled 
   at any time to know how long user has been idle. */
fuelServices.factory('idleChecker',['$interval', function($interval){
    var self = {
        secondsIdle: 0,
        init: function(){
            $(document).mousemove(function (e) {
                self.secondsIdle = 0;
            });
            $(document).keypress(function (e) {
                self.secondsIdle = 0;
            });
            $interval(function(){
                self.secondsIdle += 1;
            }, 1000)
        }
    }
    return self;
}]);

Keep in mind this idle checker will run for all routes, so it should be initialized in .run() on load of the angular app. Then you can use idleChecker.secondsIdle inside each route.

myApp.run(['idleChecker',function(idleChecker){
    idleChecker.init();
}]);

Answer 5

You can do it more elegantly with underscore and jquery-

$('body').on("click mousemove keyup", _.debounce(function(){
    // do preload here
}, 1200000)) // 20 minutes debounce

Answer 6

Debounce actually a great idea! Here version for jQuery free projects:

const derivedLogout = createDerivedLogout(30);
derivedLogout(); // it could happen that user too idle)
window.addEventListener('click', derivedLogout, false);
window.addEventListener('mousemove', derivedLogout, false);
window.addEventListener('keyup', derivedLogout, false); 

function createDerivedLogout (sessionTimeoutInMinutes) {
    return _.debounce( () => {
        window.location = this.logoutUrl;
    }, sessionTimeoutInMinutes * 60 * 1000 ) 
}