Question

How can I track the browser idle time? I am using IE8.

I am not using any session management and don’t want to handle it on server side.

Answer 1

Here is pure JavaScript way to track the idle time and when it reach certain limit do some action:

var IDLE_TIMEOUT = 60; //seconds
var _idleSecondsTimer = null;
var _idleSecondsCounter = 0;

document.onclick = function() {
    _idleSecondsCounter = 0;
};

document.onmousemove = function() {
    _idleSecondsCounter = 0;
};

document.onkeypress = function() {
    _idleSecondsCounter = 0;
};

_idleSecondsTimer = window.setInterval(CheckIdleTime, 1000);

function CheckIdleTime() {
     _idleSecondsCounter++;
     var oPanel = document.getElementById("SecondsUntilExpire");
     if (oPanel)
         oPanel.innerHTML = (IDLE_TIMEOUT - _idleSecondsCounter) + "";
    if (_idleSecondsCounter >= IDLE_TIMEOUT) {
        window.clearInterval(_idleSecondsTimer);
        alert("Time expired!");
        document.location.href = "logout.html";
    }
}

#SecondsUntilExpire { background-color: yellow; }

You will be auto logged out in <span id="SecondsUntilExpire"></span> seconds.

​This code will wait 60 seconds before showing alert and redirecting, and any action will “reset” the count – mouse click, mouse move or key press.

It should be as cross browser as possible, and straight forward. It also support showing the remaining time, if you add element to your page with ID of SecondsUntilExpire.

The above code should work fine, however has several downsides, e.g. it does not allow any other events to run and does not support multiply tabs. Refactored code that include both of these is following: (no need to change HTML)

var IDLE_TIMEOUT = 60; //seconds
var _localStorageKey = 'global_countdown_last_reset_timestamp';
var _idleSecondsTimer = null;
var _lastResetTimeStamp = (new Date()).getTime();
var _localStorage = null;

AttachEvent(document, 'click', ResetTime);
AttachEvent(document, 'mousemove', ResetTime);
AttachEvent(document, 'keypress', ResetTime);
AttachEvent(window, 'load', ResetTime);

try {
    _localStorage = window.localStorage;
}
catch (ex) {
}

_idleSecondsTimer = window.setInterval(CheckIdleTime, 1000);

function GetLastResetTimeStamp() {
    var lastResetTimeStamp = 0;
    if (_localStorage) {
        lastResetTimeStamp = parseInt(_localStorage[_localStorageKey], 10);
        if (isNaN(lastResetTimeStamp) || lastResetTimeStamp < 0)
            lastResetTimeStamp = (new Date()).getTime();
    } else {
        lastResetTimeStamp = _lastResetTimeStamp;
    }

    return lastResetTimeStamp;
}

function SetLastResetTimeStamp(timeStamp) {
    if (_localStorage) {
        _localStorage[_localStorageKey] = timeStamp;
    } else {
        _lastResetTimeStamp = timeStamp;
    }
}

function ResetTime() {
    SetLastResetTimeStamp((new Date()).getTime());
}

function AttachEvent(element, eventName, eventHandler) {
    if (element.addEventListener) {
        element.addEventListener(eventName, eventHandler, false);
        return true;
    } else if (element.attachEvent) {
        element.attachEvent('on' + eventName, eventHandler);
        return true;
    } else {
        //nothing to do, browser too old or non standard anyway
        return false;
    }
}

function WriteProgress(msg) {
    var oPanel = document.getElementById("SecondsUntilExpire");
    if (oPanel)
         oPanel.innerHTML = msg;
    else if (console)
        console.log(msg);
}

function CheckIdleTime() {
    var currentTimeStamp = (new Date()).getTime();
    var lastResetTimeStamp = GetLastResetTimeStamp();
    var secondsDiff = Math.floor((currentTimeStamp - lastResetTimeStamp) / 1000);
    if (secondsDiff <= 0) {
        ResetTime();
        secondsDiff = 0;
    }
    WriteProgress((IDLE_TIMEOUT - secondsDiff) + "");
    if (secondsDiff >= IDLE_TIMEOUT) {
        window.clearInterval(_idleSecondsTimer);
        ResetTime();
        alert("Time expired!");
        document.location.href = "logout.html";
    }
}

The refactored code above is using local storage to keep track of when the counter was last reset, and also reset it on each new tab that is opened which contains the code, then the counter will be the same for all tabs, and resetting in one will result in reset of all tabs. Since Stack Snippets do not allow local storage, it’s pointless to host it there so I’ve made a fiddle:
http://jsfiddle.net/yahavbr/gpvqa0fj/3/