How can PHP developers optimize the efficiency of tracking and displaying user online status in their applications?

To optimize the efficiency of tracking and displaying user online status in PHP applications, developers can implement a system that updates the user's status in real-time using AJAX requests. By periodically sending requests to update the user's status, the application can display the most current information without the need for constant page refreshes.

// Update user online status
function updateUserStatus($userId) {
    // Update user status in the database
}

// AJAX endpoint to update user status
if(isset($_POST['userId'])) {
    $userId = $_POST['userId'];
    updateUserStatus($userId);
}