app.js

const { createServer } = require('http');
const express = require('express');
const bodyParser = require('body-parser');
const { createEventAdapter } = require('@slack/events-api');
const { createMessageAdapter } = require('@slack/interactive-messages');
const slackSigningSecret = process.env.SLACK_SIGNING_SECRET;
const port = process.env.PORT || 3000;
const slackEvents = createEventAdapter(slackSigningSecret);
const slackInteractions = createMessageAdapter(slackSigningSecret);

// Create an express application
const app = express();

// Plug the adapter in as a middleware
app.use('/slack/events', slackEvents.requestListener());

// Plug the adapter in as a middleware
app.use('/slack/actions', slackInteractions.requestListener());

// Example: If you're using a body parser, always put it after the event adapter in the middleware stack
app.use(bodyParser());

// Initialize a server for the express app - you can skip this and the rest if you prefer to use app.listen()
const server = createServer(app);
server.listen(port, () => {
  // Log a message when the server is ready
  console.log(`Listening for events on ${server.address().port}`);
});


slackEvents.on('message', () => {

});

// Example of handling static select (a type of block action)
slackInteractions.action({ type: 'static_select' }, (payload, respond) => {
  // Logs the contents of the action to the console
  console.log('payload', payload);

  // Send an additional message to the whole channel
  doWork()
    .then(() => {
      respond({ text: 'Thanks for your submission.' });
    })
    .catch((error) => {
      respond({ text: 'Sorry, there\'s been an error. Try again later.' });
    });

  // If you'd like to replace the original message, use `chat.update`.
  // Not returning any value.
});