Bug 1102849 - Register and show events of a Room

```js
var account = aNewParticipant.account;
var name = aNewParticipant.displayName;
```
```js
var filteredJoined = aLastParticipants.filter((participant) => {
   return (participant.account && participant.account !== account) || (participant.displayName !== name);
});

if (filteredJoined.length < aLastParticipants.length) {
  // new joined user
}
```

or if you prefer keep your code please save both references