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

I use this approach, since you don't need to constantly reset the time when an event fires, instead we just record the time, this generates the idle start point.

           function idle(WAIT_FOR_MINS, cb_isIdle) {
            var self = this, 
                idle,
                ms = (WAIT_FOR_MINS || 1) * 60000,
                lastDigest = new Date(),
                watch;
            //document.onmousemove = digest;
            document.onkeypress = digest;
            document.onclick = digest;

            function digest() {
               lastDigest = new Date(); 
            }
            // 1000 milisec = 1 sec
            watch = setInterval(function(){
                if (new Date() - lastDigest > ms && cb_isIdel) {
                    clearInterval(watch);
                    cb_isIdle();
                }

            }, 1000*60);    
        },