websocket.js

const fastify = require('fastify')();
const Websocket = require('ws');
const wsServer = new Websocket.Server({
    port:3000,
    server: fastify.server
});

fastify.decorate('ws',wsServer);

fastify.ready((err)=>{
    if(err) throw Error(err);
    fastify.ws.on('connection',(socket)=>{
        socket.room = []
        socket.on('message',(message)=>{
            const data = JSON.parse(message);
            if(data.operation === 'join'){
                socket.room.push(data.roomId);
            }else if(data.operation === 'send'){
                wsServer.clients.forEach((client)=>{
                    if( client.readyState === 1 && 
                        client.room.indexOf(data.roomId) !== -1){
                            client.send(data.message);
                        }
                })
            }
        })
        socket.send("wwww");
    })
})

fastify.listen(8000);