pubnub/docs-snippets/getting-started.ts

Publish & Subscribe Real-time Messaging with PubNub

import PubNub, { PubNubError, Subscription } from '../lib/types';

// snippet.gettingStartedInitPubnub
const pubnub = new PubNub({
  publishKey: 'YOUR_PUBLISH_KEY',
  subscribeKey: 'YOUR_SUBSCRIBE_KEY',
  userId: 'YOUR_USER_ID',
});
// snippet.end

// snippet.gettingStartedEventListeners
// Add listener to handle messages, presence events, and connection status
pubnub.addListener({
  message: function (event: Subscription.Message) {
    // Handle message event
    console.log('New message:', event.message);
    // Format and display received message
    const displayText = (() => {
      if (typeof event.message === 'object' && event.message && 'text' in event.message) {
        const messageObj = event.message as { text?: string; sender?: string };
        return `${messageObj.sender || 'User'}: ${messageObj.text}`;
      } else {
        return `Message: ${JSON.stringify(event.message)}`;
      }
    })();
    console.log(displayText);
  },
  presence: function (event: Subscription.Presence) {
    // Handle presence event
    console.log('Presence event:', event);
    console.log('Action:', event.action); // join, leave, timeout
    console.log('Channel:', event.channel);
  },
  status: function (event) {
    // Handle status event
    if (event.category === 'PNConnectedCategory') {
      console.log('Connected to PubNub chat!');
      console.log('Your user ID is:', pubnub.userId);
    } else if (event.category === 'PNNetworkIssuesCategory') {
      // if eventEngine is not enabled, this event will be triggered when subscription encounter network issues.
      console.log('Connection lost');
      // handle reconnection
    } else if (event.category === 'PNDisconnectedUnexpectedlyCategory') {
      // If enableEventEngine: true set in the constructor, this event will be triggered when the connection is lost.
      console.log('Disconnected unexpectedly.');
    }
  },
});
// snippet.end

// snippet.gettingStartedCreateSubscription
// Create a channel entity
const channel = pubnub.channel('hello_world');

// Create a subscription
const subscription = channel.subscription({
  receivePresenceEvents: true, // to receive presence events
});

// Subscribe
subscription.subscribe();
// snippet.end

// snippet.gettingStartedPublishMessages
// Function to publish a message
async function publishMessage(text: string) {
  if (!text.trim()) return;

  try {
    const result = await pubnub.publish({
      message: {
        text: text,
        sender: pubnub.userId,
        time: new Date().toISOString(),
      },
      channel: 'hello_world',
    });
    console.log(`Message published with timetoken: ${result.timetoken}`);
    console.log(`You: ${text}`);
  } catch (error) {
    console.error(
      `Publish failed: ${error}.${
        (error as PubNubError).status ? ` Additional information: ${(error as PubNubError).status}` : ''
      }`,
    );
  }
}

// Example: publish a message
const text_message = 'Hello, world!';
publishMessage(text_message);

// snippet.end