title: What event is fired when a Discord bot joins a guild?
body: <p>I'm using Discord.js to create a basic Discord bot. When the bot is first started, I run <code>client.guilds.array()</code> to get a list of all guilds that the bot is currently subscribed to. I save this to a database that's used by other programs.</p>
  
  <p>However, as people add / remove the bot from their guilds, I'd like to keep an updated list of guilds. I realize I could just re-run <code>clients.guilds.array()</code> every minute or something, but that seems inefficient.</p>
  
  <p>Is there an event that fires when your bot is added to a guild and/or channel? From what I've read, the <code>guildMemberAdd</code> event seems to fire for all users / bots who are <em>already</em> subscribed to the guild. Is there any such event to let your bot know when it's been added to a guild?</p>