Detecting Idle Time in JavaScript

Introduction:

In web development, understanding user activity is crucial for optimizing performance and providing a better user experience. Detecting idle time, defined as a period of inactivity or low CPU usage, can help you trigger actions like preloading content or user authentication.

JavaScript Implementation:

To detect idle time in JavaScript, you can utilize the following vanilla JavaScript approach:

Code Snippet:

var inactivityTime = function () {
    var time;
    window.onload = resetTimer;
    // DOM Events
    document.onmousemove = resetTimer;
    document.onkeydown = resetTimer;

    function logout() {
        alert("You are now logged out.")
        //location.href = 'logout.html'
    }

    function resetTimer() {
        clearTimeout(time);
        time = setTimeout(logout, 3000)
        // 1000 milliseconds = 1 second
    }
};

Usage:

To initialize idle time detection, call the inactivityTime() function after the page has loaded:

window.onload = function() {
  inactivityTime();
}

Customization:

You can add more DOM events to monitor user activity. Some of the most commonly used events are:

document.onload = resetTimer;
document.onmousemove = resetTimer;
document.onmousedown = resetTimer; // touchscreen presses
document.ontouchstart = resetTimer;
document.onclick = resetTimer;     // touchpad clicks
document.onkeydown = resetTimer;   // onkeypress is deprectaed
document.addEventListener('scroll', resetTimer, true); // improved; see comments

For better customization, you can use an array to register multiple events:

window.addEventListener('load', resetTimer, true);
var events = ['mousedown', 'mousemove', 'keypress', 'scroll', 'touchstart'];
events.forEach(function(name) {
 document.addEventListener(name, resetTimer, true);
});

By customizing the events you monitor, you can tailor idle time detection to fit your specific application's needs.