Answers for "how to see if a user is in the server discordjs"

check user by id discord js

if(!message.author.id ==`329023088517971969` || !message.member.hasPermission(['MANAGE_GUILD'])) return message.channel.send(`You don't have the permissions to do this!`)
<code here>

discord.js check if member is in server

// guild = server
let guild = client.guilds.get('guild ID here'),
  USER_ID = '123123123';

if (guild.member(USER_ID)) {
  // there is a member in this guild with that ID
}