Telegram Bots with Node.js

Telegram has been my go to chat platform for a couple of years now. I've been able to automate A LOT of things with it such as

What are we going to build?

We'll build two things during this project

A Telegram bot that takes an input, runs a function and returns the output
Connect our app to a Web3 RPC Node, in this cause we'll use Quicknode so please go ahead and make an account on Quicknode.io

CleanShot 2022-07-21 at 21 51 00

Project setup

Please follow this guide to set up a Node.js project.
Setup a free Quicknode endpoint and choose ETH Mainnet

insert screenshot here

Create a bot via BotFather

BotFather is the official way of creating bots on Telegram.

start the bot by chatting with BotFather
execute /newbot to create a new bot
give the bot a username and a name
(optional) you can set a description and a profile picture

After you've followed this proces, you should get this text from him. CleanShot 2022-07-21 at 21 51 51

Project setup

I'm assuming you've followed this guide to setup your Node.js environment. I'll call my project telegram-bot-example.

mkdir telegram-bot-example
cd telegram-bot-example
git init
npm init -y
echo "node_modules/" > .gitignore

We'll now install the dependencies

node-telegram-bot-api for the Telegram bot
dotenv for the environment variables
web3 for connecting to the Web3 RPC Node we now have thanks to Quicknode

npm i node-telegram-bot-api dotenv web3

Defining the environment variables

Create a file called .env
for the CLI lovers
```
touch .env
```
Copy the following content into it
```
TELEGRAM_TOKEN=<INSERT_YOUR_TOKEN_HERE>
WEB3_PROVIDER_URL=<INSERT_YOUR_WEB3_PROVIDER_URL_HERE>
```
Copy and paste the URL from Quicknode and paste it in WEB3_PROVIDER_URL

Part 1: Create the Telegram bot

Create a file called app.js

Add the following code. This is the core of our bot.

app.js

const TelegramBot = require('node-telegram-bot-api');
require('dotenv').config();

const bot = new TelegramBot(process.env.TELEGRAM_TOKEN, { polling: true });
bot.on("polling_error", (msg) => console.log(msg));
bot.on('message', async (msg) => {
    const chatId = msg.chat.id;
    let text = msg.text ? msg.text : '';

    bot.sendMessage(chatId, 'hey there! this is what you asked me ' + text);
});

We don't need to pass the TELEGRAM_TOKEN as a string anymore because it's been defined in the .env file. #lifehacks lol

Run the bot
```
node app.js
```

Part 2: Connect to the Web3 RPC Node

Create a file called web3.js

Add the following code, we're doing a simple getBlock call

web3.js

const Web3 = require("web3");
require('dotenv').config();

async function getBlock() {
    const url = process.env.WEB3_PROVIDER_URL;
    const web3 = new Web3(url);
    const block = await web3.eth.getBlock("latest");
    return await block;
}

// getBlock().then(console.log)

module.exports = { getBlock };

See? Connecting to Web3 is not that hard anymore.

Uncomment the line getBlock().then(console.log) to test the file independently

node web3.js

You should get an output like this

{
  baseFeePerGas: 12011862285,
  difficulty: '12152901669249817',
  extraData: '0x466c6578706f6f6c2f53312f4252202d204c6973626f6e',
  gasLimit: 30000000,
  gasUsed: 9195298,
  hash: '0xbf04f30cb73aed0583999108603616027c2b4ab500daa0f33a1052d353b869f7',
  ...
}

This is the data within the latest mined block

Part 3: Custom Telegram commands

Let's extend our bot with a custom /getLatestBlock command

app.js

const TelegramBot = require('node-telegram-bot-api');
require('dotenv').config();

const bot = new TelegramBot(process.env.TELEGRAM_TOKEN, { polling: true });
bot.on("polling_error", (msg) => console.log(msg));
bot.on('message', async (msg) => {
    const chatId = msg.chat.id;
    let text = msg.text ? msg.text : '';

    if (text.includes('/getLatestBlock')) {
        bot.sendMessage(chatId, 'getting latest block...');
    }
});

The following block will wait for the user to call the command /getLatestBlock

if (text.includes('/getLatestBlock')) {
    bot.sendMessage(chatId, 'getting latest block...');
}

CleanShot 2022-07-21 at 21 54 55

Part 4: Connect the bot to the Web3 RPC Node

First we need to add the module we made earlier to the app.js file

const web3 = require('./web3');

Now we slightly modify the code to return blockhash when the user calls the command /getLatestBlock

if (text.includes('/getLatestBlock')) {
    bot.sendMessage(chatId, 'getting latest block...');
    const block = await web3.getBlock();
    bot.sendMessage(chatId, 'Latest blockhash: ' + block.hash);
}

The full code should look like this

.env

TELEGRAM_TOKEN=
WEB3_PROVIDER_URL=

app.js

const TelegramBot = require('node-telegram-bot-api');
const web3 = require('./web3');
require('dotenv').config();

const bot = new TelegramBot(process.env.TELEGRAM_TOKEN, { polling: true });
bot.on("polling_error", (msg) => console.log(msg));
bot.on('message', async (msg) => {
    const chatId = msg.chat.id;
    let text = msg.text ? msg.text : '';

    if (text.includes('/getLatestBlock')) {
        const block = await web3.getBlock();
        bot.sendMessage(chatId, 'Latest blockhash: ' + block.hash);
    }
});

web3.js

const Web3 = require("web3");
require('dotenv').config();

async function getBlock() {
    const url = process.env.WEB3_PROVIDER_URL;
    const web3 = new Web3(url);
    const block = await web3.eth.getBlock("latest");
    return await block;
}

module.exports = { getBlock };

You can view the full project code here

Conclusion

What have we learned?

Create a simple Telegram bot
Register and create a account at Quicknode
Connect the bot to the Web3 RPC Node
Custom Telegram commands /getLatestBlock
Environment variables such as TELEGRAM_TOKEN and WEB3_PROVIDER_URL
Export functions to be used in other files, like how the function getBlock() in web3.js was used in app.js
```
module.exports = { getBlock };
```

Next steps?

That's for you to find out

Learn how to reister the custom commands via BotFather
Create more custom commands and play around with the possibilities of Web3

Maybe getting the ETH balance of a wallet? Hmmmm ....

Thanks for reading!