Lately I've been working a lot with Discord.js
and let me tell you, it's pretty dangerous!
Although the API is a little rough to get started with, once you are familiar with how certain things work like the User, Message, and Client objects - you can do quite a lot. I've created bots that automatically assign roles to all users, or only those users who react to certain posts. I have created bots that can query a database and return information that matches up with their ID in Discord. You have complete access to your Discord community through Discord.js with Node.js.
This has lead developers to do amazing things. There is a community hosted website that focuses on outlining the coolest bots available, and the best part is that you can invite them to your servers.
If you've got any questions about getting started with Discord.js or if you've got questions about how it works feel free to ask. I would be more then happy to have a conversation on it! Thanks for reading.