How to list all MongoDB databases in Node.js?

Use db.admin().listDatabases.

You can do this now with the Node Mongo driver (tested with 3.5)

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017/";
const client = new MongoClient(url, { useUnifiedTopology: true }); // useUnifiedTopology removes a warning

// Connect
client
  .connect()
  .then(client =>
    client
      .db()
      .admin()
      .listDatabases() // Returns a promise that will resolve to the list of databases
  )
  .then(dbs => {
    console.log("Mongo databases", dbs);
  })
  .finally(() => client.close()); // Closing after getting the data