My room did nothing when a peer has joined?

[fCorleone]

I was following the demo video on youtube: https://www.youtube.com/watch?v=Nv_Teb--1zg
But when I add a room in my code and test it. The console gives no reactions when another peer joined the room.
Here's my code:

const IPFS = require('ipfs')
const Room = require('ipfs-pubsub-room')

const ipfs = new IPFS({
	repo: repo(),
	EXPERIMENTAL: {
		pubsub : true
	}
})

ipfs.once('ready', () => ipfs.id((err,info) => {
	if (err) {throw err}
	console.log('IPFS is ready with the address ' + info.id)
}))

const room = Room(ipfs, 'ipfs-pubsub-room-demo')
console.log(room.id)
room.on('peer joined', (peer) => console.log('some peer '+ peer +' has joined'))
room.on('peer left', (peer) => console.log('some peer '+ peer +' has left'))

function repo () {
	return 'ipfs/pubsub-demo/' + Math.random()
}

And when I test the code on Chrome, the console only gives the ID of the node, but no messages like 'some peer XXXX has joined.'