How to create a Telegram Bot using NodeJS

Débora — Fri, 13 Jan 2023 17:10:04 +0000

In this tutorial, we will create a simple bot that will send a random joke from a list of jokes and a random cat image to your chat.

Prerequisites

You should have NodeJS installed for this tutorial. If you don't have it, you can download it from here.

Creating the bot

First, you need to create a bot. Telegram make it really easy, and all you need to do is to talk to the BotFather. Send a message, and then follow the instructions. You can find the BotFather here.

When you open it, click on the start button, and then send the /newbot command. Follow the instructions, and you will get a token for your bot. Save it, you will need it later.

Creating the NodeJS project

Create a new folder for your project, and open it in the terminal.

To create a NodeJS project, you can use the npm init command. This will create a package.json file, that will contain all the information about your project. You can also use the -y flag to skip the questions.

npm init -y

Installing the dependencies

In this project we will use the Telegraf library to create the bot. To install it, you can use the npm install command.

npm install telegraf

This will install the library and all the dependencies.
There are other libraries that you can use to create a bot, but I prefer Telegraf because it is really easy to use.

We also will use the folowing libraries:

dotenv to load the environment variables
axios: to make HTTP requests
express: to create the server

We can install all of them using the npm install command.

npm install dotenv axios express

If you do not know any of those libraries, that is okay and we are going very light on them. You can read more about them in the documentation.

Creating the server

First, we need to create a server to run our bot. We will use the express library to create it.
In the root of your project, create a new file called index.js and add the following code:

const express = require("express");
const app = express();

app.use(express.json());

app.get("/", (req, res) => {
  res.send("Hello World!");
});

app.listen(3000, () => {
  console.log("Server running on port 3000");
});

This will create a server that will listen on port 3000. You can change it if you want.

To run the server, you can use the node command.

node index.js

Or you can use the nodemon library to run it. This will restart the server every time you make a change.

npm install -g nodemon
nodemon

If you open your browser and go to http://localhost:3000, you should see the Hello World! message. If you don't, check the console for errors.

This endpoint will be used only for this test, so you can remove it later.

Creating the bot

At the root of your project, create a new file called .env and add the following

BOT_TOKEN=your_token

Add your token that you got from BotFather.

Import the dotenv library and Telegraf at the top of your index.js.

const { Telegraf } = require("telegraf");

require("dotenv").config();

Then, create a new instance of the class, passing the token as a parameter.

const bot = new Telegraf(process.env.BOT_TOKEN);

This part can be a bit confusing, so let's break it down.

Ngrok

We need to create a Webhook to receive the messages from Telegram.

First, install Ngrok. You can find the instructions here.

Then, run it with the following command:

ngrok http 3000

This will create a tunnel to your local server. It should be running on the same port that your node server is running. You should see something like this on the console:

IMAGE

Copy the URL that is in the Forwarding section. On the index create a const called WEBHOOK_URL and add the URL.

const WEBHOOK_URL = "https://your_url";

Setting the Webhook

Telegraf does have a method to set the Webhook, but I found it easier to set it using a request. So, we will use the setWebhook method from Telegram API.
To use it, first you should create const with the link to the API, token and URL of the Webhook.

Import the axios library at the top of your index.js.

const axios = require("axios");

Create a const called TELEGRAM_API and add the following code:

const TELEGRAM_API = `https://api.telegram.org/bot${process.env.BOT_TOKEN}`;

And create a function to set the Webhook that makes a post to the setWebhook endpoint.

const setWebhook = async () => {
  try {
    const response = await axios.post(
      `${TELEGRAM_API}/setWebhook?url=${WEBHOOK_URL}`
    );
    console.log(response.data);
  } catch (error) {
    console.log(error);
  }
};

Call the function to set the Webhook inside the app.listen function.

app.listen(3000, async () => {
  console.log("Server running on port 3000");
  await setWebhook();
});

This function will make a POST request to the API, passing the URL of the Webhook. If everything goes well, you should see the following message on the console:

{ ok: true, result: true, description: 'Webhook was set' }

Starting the bot

To start the bot, you can use the bot.launch method.

bot.launch();

This will start the bot and listen for messages.

Your index.js should look like this:

const express = require("express");
const axios = require("axios");
const { Telegraf } = require("telegraf");

require("dotenv").config();

const app = express();

app.use(express.json());

const bot = new Telegraf(process.env.BOT_TOKEN);

const WEBHOOK_URL = "https://dbaf-192-144-124-11.sa.ngrok.io";
const TELEGRAM_API = `https://api.telegram.org/bot${process.env.BOT_TOKEN}`;

const setWebhook = async () => {
  try {
    const response = await axios.post(
      `${TELEGRAM_API}/setWebhook?url=${WEBHOOK_URL}`
    );
    console.log(response.data);
  } catch (error) {
    console.log(error);
  }
};

bot.launch();

app.get("/", (req, res) => {
  res.send("Hello World!");
});

app.listen(3000, async () => {
  console.log("Server running on port 3000");
  await setWebhook();
});

Sending a message

We can set a command that when you type /start the bot will send a message.

bot.start((ctx) => ctx.reply("Hello World!"));

If you go to Telegram and type /start, you should see the message.

Random Joke

To send a random joke, we will use the Official Joke API. It is a free API that returns a random joke. To use it, we need to make a GET request to the API and get the joke from the response.

bot.command("joke", async (ctx) => {
  try {
    const response = await axios.get(
      "https://official-joke-api.appspot.com/random_joke"
    );
    const { setup, punchline } = response.data;
    const message = `${setup}\n${punchline}`;
    ctx.reply(message);
  } catch (error) {
    console.log(error);
  }
});

If you go to Telegram and type /joke, you should see a random joke.

Sending a photo

To send a photo, we will use the Cat API. It is a free API that returns a random cat image. To use it, we need to make a GET request to the API and get the image from the response.

bot.command("cat", async (ctx) => {
  try {
    const response = await axios.get(
      "https://api.thecatapi.com/v1/images/search"
    );
    const { url } = response.data[0];
    ctx.replyWithPhoto(url);
  } catch (error) {
    console.log(error);
  }
});

Same trick, if you send a message to your bot with /cat, you should see a random cat image.

Conclusion

Congratulations! You have created your first Telegram bot.
You can find the code on GitHub.

DEV Community: Débora

How to create a Telegram Bot using NodeJS

Prerequisites

Creating the bot

Creating the NodeJS project

Installing the dependencies

Creating the server

Creating the bot

Ngrok

Setting the Webhook

Starting the bot

Sending a message

Random Joke

Sending a photo

Conclusion