title: Check if user ID exists in Discord server
body: <p>My Discord bot needs to check whether a user is in the server or not. I'm using node.js and discord.js.</p>
  
  <pre><code>var USER_ID = randomNumbers
  if (client.guild.member(USER_ID).exists){
     do something
  }
  </code></pre>
  
  <p>Is there a way to do this?</p>