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("
Welcome Back.
");            
            }

            idleState = false;

            idleTimer = setTimeout(function () { 

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

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

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

    });
}) (jQuery)