Laravel Echo (Pusher) initial channel subscribed event

websockets.js

// Subscribe to channel 'user.$id'
window.Echo.private('user.' + window.Laravel.user)
    .listen('PrivateEvent', (e) => {
        console.log(e);
    });

// Get pusher instance and add pushers cahnnel event to detect when the channel is subscribed
window.Echo.connector.pusher.channels.channels['private-user.' + window.Laravel.user].bind('pusher:subscription_succeeded', function() {
    console.log('channel subscription suceeded');
});