node.js

const Ably = require("ably");
// Create the client
const ably = new Ably.Realtime.Promise({
  authUrl: "https://ably.com/ably-auth/token/docs",
});

// wrapper for async functions
const ablyRealtimePromiseExample = async () => {
  // Connect to Ably
  await ably.connection.once("connected");
  console.log("Connected to Ably!");

  // get the channel to subscribe to
  const channel = ably.channels.get("quickstart");

  /* 
    Subscribe to a channel. 
    The promise resolves when the channel is attached 
    (and resolves synchronously if the channel is already attached).
  */
  await channel.subscribe("greeting", (message) => {
    console.log("Message is ==> " + message.data);
  });

  // Publish a message or two
  await channel.publish("greeting", "hello!");
  await channel.publish("greeting", "hello!");
  await channel.publish("greeting", "hello!");

  // wait 2s to receive all messages and then shut down
  setTimeout(() => {
    console.log("Closing connection...");
    ably.close();
    console.log("Closed the connection to Ably.");
  }, 2000);
};

// call wrapper
ablyRealtimePromiseExample();