https://medium.com/@hang.c/build-a-multi-platform-chatbot-with-botkit-c3b74c095cb2

bot.js

// Load Environment variables from dotenv
require('dotenv').config();

const express = require("express");
const bodyParser = require("body-parser");
// Import Botkit's core features
const { Botkit } = require("botkit");
// Import a platform-specific adapter for slack.
const { SlackAdapter, SlackEventMiddleware } = require('botbuilder-adapter-slack');

// Create an express server with json and urlencoded body parsing
const webserver = express();
webserver.use((req, res, next) => {
    req.rawBody = '';
    req.on('data', function (chunk) {
        req.rawBody += chunk;
    });
    next();
});
webserver.use(bodyParser.json());
webserver.use(bodyParser.urlencoded({ extended: true }));

// Adaptor for Slack
const slackAdaptor = new SlackAdapter({
    // REMOVE THIS OPTION AFTER YOU HAVE CONFIGURED YOUR APP!
    enable_incomplete: true,
    // The following options are sufficient for a single team application
    // parameters used to secure webhook endpoint
    verificationToken: process.env.SLACK_VERIFICATION_TOKEN,
    clientSigningSecret: process.env.SLACK_CLIENT_SIGNING_SECRET,
    // auth token for a single-team app
    botToken: process.env.SLACK_BOT_TOKEN
});

// Use SlackEventMiddleware to emit events that match their original Slack event types.
slackAdaptor.use(new SlackEventMiddleware());

// Controller for Slack
const slackController = new Botkit({
    webhook_uri: process.env.SLACK_WEBHOOK_URI,
    adapter: slackAdaptor,
    webserver: webserver
});

// Controller for Teams
const teamsController = new Botkit({
    webhook_uri: process.env.TEAMS_WEBHOOK_URI,
    adapterConfig: {
        appId: process.env.TEAMS_APP_ID,
        appPassword: process.env.TEAMS_APP_PASSWORD,
    },
    webserver: webserver
});

// load developer-created local custom feature modules.
// Load common features for slack and teams
slackController.loadModules(__dirname + '/features/common');
teamsController.loadModules(__dirname + '/features/common');
// Load platform specific features seperately
slackController.loadModules(__dirname + '/features/slack');
teamsController.loadModules(__dirname + '/features/teams');

// For running server locally for development purposes
if (require.main === module) {
    const http = require("http");
    const port = process.env.PORT || 3000;
    const httpserver = http.createServer(webserver);
    httpserver.listen(port, function () {
        console.log("Slack Webhook endpoint online:  http://127.0.0.1:" + port + process.env.SLACK_WEBHOOK_URI);
        console.log("Teams Webhook endpoint online:  http://127.0.0.1:" + port + process.env.TEAMS_WEBHOOK_URI);
    });
};