What shall I do with 'private-' prefix for private channels in laravel?

The realtime Laravel application made by socket.io, laravel-echo, redis I am talking about is in localhost/br1. I created a simple private event as follow

namespace App\Events;

use App\User;
use Illuminate\Broadcasting\Channel;
use Illuminate\Queue\SerializesModels;
use Illuminate\Broadcasting\PrivateChannel;
use Illuminate\Broadcasting\PresenceChannel;
use Illuminate\Foundation\Events\Dispatchable;
use Illuminate\Broadcasting\InteractsWithSockets;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;

class PrivateEvent implements ShouldBroadcast
{
    use Dispatchable, InteractsWithSockets, SerializesModels;

    /**
     * Create a new event instance.
     *
     * @return void
     */

    public $user;
    public function __construct(User $user)
    {
        $this->user = $user;
    }

    /**
     * Get the channels the event should broadcast on.
     *
     * @return \Illuminate\Broadcasting\Channel|array
     */
    public function broadcastOn()
    {
        return new PrivateChannel('user.' . $this->user->id);
    }
}

and in channels.php

Broadcast::channel('user.{id}', function ($user, $id) {
    return (int) $user->id === (int) $id;
});

and route

Route::get('test-broadcast', function(){
    broadcast(new \App\Events\PrivateEvent(auth()->user()));
});

and script

<script>
    window.Laravel = {!! json_encode([
    'user' => auth()->check() ? auth()->user()->id : null,
]) !!};
</script>

which is in head and

<script src="https://cdn.socket.io/socket.io-1.4.5.js"></script>
<script src=""></script>
<script type="text/javascript">
    document.onreadystatechange = () => {
        if (document.readyState === 'complete') {
            console.log("doc is ready");
            window.Echo.private('user.'+window.Laravel.user)
                .listen('PrivateEvent', (e) => {
                    console.log(e);
                });
        }
    };
</script>

in welcome.blade.php.

after running queue and npm run dev and starting laravel-echo-server , I face two problems:

1- After starting laravel echo server or visiting the url containing welcome.blade.php I see this

2- After visiting page /test-broadcast the terminal prints message

Channel: private-user.2

Event: App\Events\PrivateEvent

what is this private-? and how does this prefix will effect the way I must name and call the events?

via Chebli Mohamed