React Hooks
import React, { useState, useEffect } from 'react';
function FriendStatus(props) {
const [isOnline, setIsOnline] = useState(null); useEffect(() => { function handleStatusChange(status) { setIsOnline(status.isOnline); } ChatAPI.subscribeToFriendStatus(props.friend.id, handleStatusChange); return () => { ChatAPI.unsubscribeFromFriendStatus(props.friend.id, handleStatusChange); }; });
if (isOnline === null) {
return 'Loading...';
}
return isOnline ? 'Online' : 'Offline';
}