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

As simple as it can get, detect when mouse moves only:

var idle = false;

document.querySelector('body').addEventListener('mousemove', function(e) {
    if(idle!=false)idle = false;
});

var idleI = setInterval(function()
{   
    if(idle == 'inactive')
    {
        return;
    }

    if(idle == true)
    {
        idleFunction();
        idle = 'inactive';
        return;
    }

    idle = true;
}, 30000);// half the expected time, idle will trigger after 60s in this case.

function idleFuntion()
{
   console.log('user is idle');
}