member-count.js

module.exports = client => {
  const channelId = 'Your Channel Id'

  const updateMembers = guild => {
    const channel = guild.channels.cache.get(channelId)
    channel.setName(`🍪┃Members: ${guild.memberCount.toLocaleString()}`)
    // 500 -> 500
    // 1300 -> 13,00
  }
  client.on('guildMemberAdd', member => updateMembers(member.guild))
  client.on('guildMemberRemove', member => updateMembers(member.guild))

  const guild = client.guilds.cache.get('Your Server Id')
  updateMembers(guild)
}