user count discord.js source code example
Example: Bots member count discord js
<client>.guilds.cache.reduce((a, g) => a + g.memberCount, 0)
// The client is the bot itself.
// You would have defined this at the top of your index.js/app.js
// It would look like 'const client = new Discord.Client()'
// Put that in place for '<client>' and remove the <>