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

My answer was inspired by vijay's answer, but is a shorter, more general solution that I thought I'd share for anyone it might help.

(function () { 
    var minutes = true; // change to false if you'd rather use seconds
    var interval = minutes ? 60000 : 1000; 
    var IDLE_TIMEOUT = 3; // 3 minutes in this example
    var idleCounter = 0;

    document.onmousemove = document.onkeypress = function () {
        idleCounter = 0;
    };

    window.setInterval(function () {
        if (++idleCounter >= IDLE_TIMEOUT) {
            window.location.reload(); // or whatever you want to do
        }
    }, interval);
}());

As it currently stands, this code will execute immediately and reload your current page after 3 minutes of no mouse movement or key presses.

This utilizes plain vanilla JavaScript and an immediately-invoked function expression to handle idle timeouts in a clean and self-contained manner.