Installing and Using NVM (Node Version Manager)

Yarn is an efficient tool for managing dependencies in Node.js-based projects. It is known for its high speed, security, and ease of use. What is Yarn and Why Use It? Yarn is an alternative to the standard npm (Node Package Manager). It is designed to handle packages and projects built on Node.js. Yarn offers several advantages over npm: Speed: Yarn downloads packages in parallel, significantly reducing installation time. Security: The use of a yarn.lock file helps prevent version conflicts. Deterministic Builds: Ensures identical package versions across different machines. User-Friendly Interface: Cleaner command syntax and additional tools for dependency management. If your project involves working with many packages and dependencies, using Yarn can greatly simplify the task. It allows for faster and more secure package installations while making dependency management more predictable — a valuable benefit for team-based projects. Comparison of Yarn and npm Yarn's advantages make it particularly appealing for developers, especially in large-scale projects. Feature Yarn npm Installation Speed Faster thanks to caching Slower Dependency Handling Deterministic builds Potential version conflicts Lock File yarn.lock package-lock.json Ease of Use Simplified syntax More standard interface Installing Yarn Before installing Yarn, ensure that Node.js and npm are installed: Open the terminal or command prompt. Run the following commands to check the versions of Node.js and npm: node -vnpm -v If Node.js or npm is not installed, download them from the official Node.js website. You may also find our installation guide helpful. To install Yarn globally, run: npm install -g yarn Check if Yarn was installed successfully: yarn --version If the command returns the version number, Yarn has been installed correctly. Yarn Commands Yarn's intuitive syntax makes it easy to manage your project dependencies efficiently. Project Initialization To get started with Yarn, initialize your project to create a package.json file containing project and dependency information. Navigate to your project directory: cd your-project-directory Run the following command and follow the prompts: yarn init This will generate a package.json file with basic project settings. Installing Packages To install a single package: yarn add <package-name> This adds the specified package to your project. To install a package as a development dependency: yarn add <package-name> --dev This is useful for packages required only during development. To install a specific version of a package: yarn add <package-name>@<version> This allows you to select the desired package version. Installing All Dependencies If the project already contains a package.json or yarn.lock, run: yarn install This is helpful when cloning a project from a repository to quickly set up the environment. Removing Packages To remove a package from your project and update package.json, use: yarn remove <package-name> Updating Dependencies To upgrade packages to their latest versions, run: yarn upgrade This ensures your project uses the most current versions. Dependency Security Audit To identify vulnerabilities in your project dependencies: yarn audit This helps detect and address potential security threats. Caching Yarn leverages caching to speed up subsequent package installations. To clear the cache: yarn cache clean This command can be useful if you encounter issues during package installation. Conclusion Yarn is a modern tool for managing dependencies in Node.js projects. Its speed, security features, and intuitive interface make it an excellent choice for developers.

When developing Telegram bots using Node.js, there are two main methods for receiving user messages: Polling and Webhook. Both serve the purpose of handling incoming requests, but each has its unique features, making them suitable for different scenarios. What is Polling? Polling is a method of fetching updates from the Telegram server by periodically sending requests. The bot sends requests at specific time intervals to check for new messages or events. There are two types of polling: Long Polling and Short Polling. Long Polling In Long Polling, the bot sends a request to the server and waits for a response. If there are no new messages, the server holds the request open until a new message arrives or the timeout period ends. Once the bot receives a response, it immediately sends a new request. Here’s an example where the bot is configured to poll the Telegram server every 3 seconds, with a timeout of 10 seconds: const TelegramBot = require('node-telegram-bot-api'); const token = 'TOKEN'; // Create a bot instance with Long Polling enabled const bot = new TelegramBot(token, { polling: { interval: 3000, // Interval between requests (3 seconds) autoStart: true, // Automatically start polling params: { timeout: 10 // Request timeout (10 seconds) } } }); bot.on('message', (msg) => { const chatId = msg.chat.id; const text = msg.text; // Respond to the received message bot.sendMessage(chatId, `You wrote: ${text}`); }); bot.onText(/\/start/, (msg) => { const chatId = msg.chat.id; bot.sendMessage(chatId, 'Hello! I am a bot using Long Polling.'); }); Short Polling In Short Polling, the bot sends requests to the server at short intervals, regardless of whether new messages are available. This method is less efficient because it generates more network requests and consumes more resources. In this case, the bot constantly requests updates from the server without keeping the connection open for a long time. This can lead to high network usage, especially with heavy traffic. Here’s an example of a bot using Short Polling: const TelegramBot = require('node-telegram-bot-api'); const token = 'TOKEN'; // Create a bot instance with Short Polling enabled const bot = new TelegramBot(token, { polling: true }); bot.on('message', (msg) => { const chatId = msg.chat.id; const text = msg.text; bot.sendMessage(chatId, `You wrote: ${text}`); }); bot.onText(/\/start/, (msg) => { const chatId = msg.chat.id; bot.sendMessage(chatId, 'Hello! I am a bot using Short Polling.'); }); What is Webhook? Webhook is a method that allows a bot to receive updates automatically. Instead of periodically polling the Telegram server, the bot provides Telegram with a URL, where POST requests will be sent whenever new updates arrive. This approach helps to use resources more efficiently and minimizes latency. In the following example, the bot receives requests from Telegram via Webhook, eliminating the need for frequent server polling. This reduces server load and ensures instant message handling. const TelegramBot = require('node-telegram-bot-api'); const express = require('express'); const bodyParser = require('body-parser'); const token = 'TOKEN'; // Your server URL const url = 'https://your-server.com'; const port = 3000; // Create a bot instance without automatic polling const bot = new TelegramBot(token, { webHook: true }); // Set the Webhook URL for your server bot.setWebHook(`${url}/bot${token}`); // Configure the Express server const app = express(); app.use(bodyParser.json()); // Request handler for incoming updates from Telegram app.post(`/bot${token}`, (req, res) => { bot.processUpdate(req.body); res.sendStatus(200); }); bot.on('message', (msg) => { const chatId = msg.chat.id; bot.sendMessage(chatId, `You wrote: ${msg.text}`); }); // Start the server app.listen(port, () => { console.log(`Server running on port ${port}`); }); To run the code and start the bot, install the required libraries: npm install node-telegram-bot-api express Server Setup We need to set up a server to work with Webhook. We'll use Hostman for this. Step 1: Set Up a Cloud Server Log in to your Hostman control panel and start by creating a new project. Next, create a cloud server. During the server creation process, select the Marketplace tab and choose Node.js. When the server starts, Node.js will automatically be installed. Choose the nearest region with the lowest ping. You can choose the configuration according to your needs, but for testing purposes, the minimum configuration will suffice. In the Network settings, make sure to assign a public IP. In the Authorization and Cloud-init settings, leave them unchanged.  In the server's information, specify the server name and description, and select the project created earlier. Once all settings are configured, click on the Order button. The server will start, and you will receive a free domain. Step 2: Install SSL Certificate Since Telegram's API only works with HTTPS, you need to install an SSL certificate. For this, you will need a registered domain name. To set up the web server and install the certificate, execute the following commands sequentially: Update available package lists: sudo apt update Create and open the Nginx configuration file: sudo nano /etc/nginx/sites-available/your_domain Inside this file, add the following configuration: server { listen 80; server_name your_domain; location / { proxy_pass http://localhost:3000; proxy_http_version 1.1; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection 'upgrade'; proxy_set_header Host $host; proxy_cache_bypass $http_upgrade; } } Replace your_domain with your actual domain name in this file and throughout the console. Create a symbolic link to the file: sudo ln -s /etc/nginx/sites-available/your_domain /etc/nginx/sites-enabled/ Restart Nginx: sudo systemctl restart nginx Install certbot to create SSL certificates: sudo apt install certbot python3-certbot-nginx Use certbot to configure the SSL certificate: sudo certbot --nginx -d your_domain Replace your_domain with your actual domain name. Examples of Using Polling and Webhook Before choosing a method for receiving messages, it is important to consider the characteristics of each approach and its applicability in different situations. Polling: Local Development: When developing and testing a bot on a local machine, using Long Polling allows for easy updates without the need to set up a server. Small Projects: If you are creating a bot for a small group of users or for personal use, and you do not have strict requirements for response time, Polling will be sufficient. Low Traffic Projects: If your bot is not expecting a large number of messages, using Short Polling can be appropriate as it is simple to implement. Webhook: Production Applications: For bots working in a production environment where immediate responses to events are important, Webhook is the preferred choice. For example, bots that handle payments or respond to user queries in real time should use Webhook to ensure high performance. High Traffic Systems: If you're developing a bot that will serve a large number of users, Webhook will be more efficient since it reduces server load by eliminating continuous requests. Systems with Long Operations: If your bot performs long operations (such as generating reports or processing data), Webhook can be used to notify users once these operations are complete. Comparison of Polling and Webhook To better understand the differences between the two approaches, here is a comparison table of their characteristics: Characteristic Polling Webhook Method of Data Retrieval Periodic requests to the Telegram server Automatic sending of updates to a specified URL Setup Simple setup, no additional resources required Requires HTTPS server setup and SSL certificate Response Speed May have slight delays due to polling intervals Near-instant message reception Resource Usage Continuously requests updates, taxing the server More resource-efficient since updates come automatically Infrastructure Requirements Does not require a public server Requires a public HTTPS server Reliability Does not depend on the availability of an external server Can be unavailable if there are issues with the HTTPS server Setup Issues in Local Environment Can be used locally for testing Difficult to use without public access Conclusion The choice between Polling and Webhook depends on the specific needs of your project. Polling is a simple and quick way to develop, especially in the early stages, while Webhook offers more efficient message processing for production environments.

Telegram bots have become an integral part of this messenger: every day, hundreds of thousands of people use them—and for good reason. Telegram bots are easy for users to interact with, and developers can quickly and comfortably create them thanks to the constantly evolving Telegram API, which aims to improve daily. The main idea behind Telegram bots is task automation and extending the messenger’s functionality. Bots can serve as simple assistants performing commands or as complex systems with full-fledged business logic. From sending out news updates to implementing intricate game mechanics—the possibilities for building bots are nearly limitless. With Node.js, you can implement almost any functionality for a Telegram bot, thanks to its ecosystem of libraries and frameworks. Node.js, as a platform with asynchronous request handling, is ideal for building bots that need to work in real-time and interact with thousands of users simultaneously. Here are some capabilities that can be implemented: Basic Functionality Responding to commands Inline bots Buttons Integration with External Services APIs and databases Webhooks Notifications Sending scheduled notifications or alerts when certain events occur Automatically sending news updates from sources every N seconds Analytics Collecting various statistics Creating a Telegram Bot First, you need to create a bot within Telegram. Use the official BotFather bot to register your bot. Click the "Start" button (or if you’ve already interacted with the bot, send the command /start). In BotFather’s response, find and select the /newbot command. BotFather will ask you to provide a bot name and then a username. The username must end with the word bot. For example, if your bot’s name is Tetris, the username should be one of the following: TetrisBot Tetris_bot Tetrisbot Tetris_Bot If everything is entered correctly, your bot will be created. BotFather will also give you a unique bot token, which you must keep private. Development We will create a bot that sends various quizzes in the form of Telegram polls. The quiz topics will be school subjects. The bot will have two commands: one for sending questions and another for selecting quiz topics. Preparing the Environment Before starting development, ensure that Node.js and npm are installed on your PC. You can download Node.js from the official website, and npm will be installed automatically along with Node.js. If you are using Linux, you can install npm by following this guide. Once Node.js is installed, you can begin developing the bot. First, create a new private repository on GitHub and select Node under the Add .gitignore section. Now, clone this repository to your PC using the terminal. If you want the project to be on your desktop, enter: cd Desktop Then enter: git clone https://github.com/username/School-Quiz Replace username with your actual GitHub username. You can also replace School-Quiz with any other project name. After cloning the repository, without closing the terminal, enter: cd School-Quiz Replace School-Quiz with the actual name of the folder where your project was cloned from GitHub. To initialize the project, run the following command: npm init You will be prompted to enter the package name, version, description, default entry file, test command, Git repository, keywords, author, and license. You can press "Enter" to accept the default values. Now, let’s install the library that will be used to write the bot’s code. Enter the following command in the terminal (ensuring that you are in the project folder): npm install node-telegram-bot-api Writing Code for the Quiz After the installation is complete, you can start writing the code. Open the package.json file and find the scripts section. Inside it, above the test command, add the following line: "start": "node index.js", This allows you to start the project by simply entering npm start in the terminal instead of typing node followed by the file name. Now, create a file called index.js and add the following code: const TelegramBot = require('node-telegram-bot-api'); const fs = require('fs'); const bot = new TelegramBot('TOKEN', { polling: true }); // Replace 'TOKEN' with the actual token provided by BotFather const ADMIN_ID = '1402655980'; let awaitingSupportMessage = {}; // Stores information about users waiting for support // Stores selected topics for users let userTopics = {}; // Topics and their respective question files const topics = { math: { name: 'Math', file: 'questions/math.json' }, spanish: { name: 'Spanish', file: 'questions/spanish.json' }, history: { name: 'History', file: 'questions/history.json' } }; // Function to retrieve questions based on selected topics function getQuestionsByTopics(userId) { const selectedTopics = userTopics[userId] || Object.keys(topics); let allQuestions = []; selectedTopics.forEach(topic => { const questions = JSON.parse(fs.readFileSync(topics[topic].file, 'utf8')); allQuestions = allQuestions.concat(questions); }); return allQuestions; } function getRandomQuestion(userId) { const questions = getQuestionsByTopics(userId); const randomIndex = Math.floor(Math.random() * questions.length); return questions[randomIndex]; } bot.onText(/\/quiz/, (msg) => { const chatId = msg.chat.id; const userId = msg.from.id; // Retrieve a random question const questionData = getRandomQuestion(userId); // Send the poll as a quiz bot.sendPoll( chatId, questionData.question, // The question text questionData.options, // Answer options { type: 'quiz', // Quiz type correct_option_id: questionData.correct_option_id, // Correct answer is_anonymous: false // The quiz won't be anonymous } ).then(pollMessage => { // Handle poll results bot.on('poll_answer', (answer) => { if (answer.poll_id === pollMessage.poll.id) { const selectedOption = answer.option_ids[0]; // Check if the answer is correct if (selectedOption !== questionData.correct_option_id) { bot.sendMessage(chatId, questionData.explanation); } } }); }); }); bot.onText(/\/settopic/, (msg) => { const chatId = msg.chat.id; const userId = msg.from.id; const keyboard = Object.keys(topics).map(topicKey => ({ text: `${(userTopics[userId] || []).includes(topicKey) ? '✅ ' : ''}${topics[topicKey].name}`, callback_data: topicKey })); bot.sendMessage(chatId, 'Select the topics for questions:', { reply_markup: { inline_keyboard: [keyboard] } }); }); // Topic selection handler bot.on('callback_query', (callbackQuery) => { const message = callbackQuery.message; const userId = callbackQuery.from.id; const topicKey = callbackQuery.data; // Initialize selected topics for the user if they don't exist if (!userTopics[userId]) { userTopics[userId] = Object.keys(topics); } // Add or remove the selected topic if (userTopics[userId].includes(topicKey)) { userTopics[userId] = userTopics[userId].filter(t => t !== topicKey); } else { userTopics[userId].push(topicKey); } // Update the message with buttons const keyboard = Object.keys(topics).map(topicKey => ({ text: `${userTopics[userId].includes(topicKey) ? '✅ ' : ''}${topics[topicKey].name}`, callback_data: topicKey })); bot.editMessageReplyMarkup({ inline_keyboard: [keyboard] }, { chat_id: message.chat.id, message_id: message.message_id }); }); bot.onText(/\/start/, (msg) => { const chatId = msg.chat.id; bot.sendMessage(chatId, "Hello! Type /quiz to start a quiz. Use /settopic to choose topics."); }); console.log('Bot is running.'); Quiz Questions Files Now, create a folder named questions inside your project. Within this folder, create three JSON files: spanish.json [ { "question": "How do you say 'I' in Spanish?", "options": ["Yo", "Tú", "Nosotros"], "correct_option_id": 0, "explanation": "The correct answer is: Yo." }, { "question": "What does the verb 'correr' mean?", "options": ["to run", "to walk", "to stand"], "correct_option_id": 0, "explanation": "The correct answer is: to run." }, { "question": "How do you say 'she' in Spanish?", "options": ["Tú", "Ella", "Vosotros"], "correct_option_id": 1, "explanation": "The correct answer is: Ella." } ] history.json [ { "question": "In which year did World War II begin?", "options": ["1939", "1941", "1914"], "correct_option_id": 0, "explanation": "The correct answer is: 1939." }, { "question": "Who was the first president of the United States?", "options": ["Abraham Lincoln", "George Washington", "Franklin Roosevelt"], "correct_option_id": 1, "explanation": "The correct answer is: George Washington." }, { "question": "Which country was the first to send a human into space?", "options": ["USA", "USSR", "China"], "correct_option_id": 1, "explanation": "The correct answer is: USSR." } ] math.json [ { "question": "What is 2 + 2?", "options": ["3", "4", "5"], "correct_option_id": 1, "explanation": "The correct answer is: 4." }, { "question": "What is 5 * 5?", "options": ["10", "20", "25"], "correct_option_id": 2, "explanation": "The correct answer is: 25." }, { "question": "What is 10 / 2?", "options": ["4", "5", "6"], "correct_option_id": 1, "explanation": "The correct answer is: 5." } ] Each JSON file contains the question, answer options, the index of the correct answer, and an explanation that will be sent if the user selects the wrong answer. Telegram Stars Recently, Telegram introduced an internal currency called Telegram Stars, along with an API update allowing bots to support donations in Stars. Let’s add a /donate command to the index.js file. When users send this command, the bot will generate a payment invoice. Add the following code inside index.js: bot.onText(/\/donate/, (msg) => { const chatId = msg.chat.id; bot.sendInvoice(chatId, 'Donation', 'Support the project with a donation', 'unique_payload', '', // Empty provider_token for Stars Payments 'XTR', // Currency "XTR" [{ label: 'Donation', amount: 1 }] // Amount: 1 Star ); }); Support Command Let’s add another command called /support. This command allows a large number of users to contact you without creating multiple unnecessary chats. Users will be able to send text, photos, and videos, and the bot will forward these messages directly to the admin (in this case, you). Place the following code inside index.js. At the beginning of the file, add: const ADMIN_ID = 'ID'; let awaitingSupportMessage = {}; // Stores information about users waiting for support The ADMIN_ID tells the bot where to forward the user’s message. To find your ID, you can use the Get My ID bot by simply sending the /start command to it. At the end of the file, add the following code: bot.onText(/\/support/, (msg) => { const chatId = msg.chat.id; const userId = msg.from.id; // Inform the user that we are waiting for their message bot.sendMessage(chatId, "Please send your message in a single message, including text, photos, or videos!"); // Mark the user as currently composing a support message awaitingSupportMessage[userId] = true; }); Handling All Messages This section processes all incoming messages and checks if they are part of a support request. Add the following code to handle different types of user content: bot.on('message', (msg) => { const userId = msg.from.id; // Check if the user is sending a message after the /support command if (awaitingSupportMessage[userId]) { const chatId = msg.chat.id; const caption = msg.caption || ''; // Include caption if present // Check the type of message and forward the corresponding content to the admin if (msg.text) { // If the message contains text bot.sendMessage(ADMIN_ID, `New support request from @${msg.from.username || msg.from.first_name} (ID: ${userId}):\n\n${msg.text}`); } else if (msg.photo) { // If the message contains a photo const photo = msg.photo[msg.photo.length - 1].file_id; // Select the highest resolution photo bot.sendPhoto(ADMIN_ID, photo, { caption: `New support request from @${msg.from.username || msg.from.first_name} (ID: ${userId})\n\n${caption}` }); } else if (msg.video) { // If the message contains a video const video = msg.video.file_id; bot.sendVideo(ADMIN_ID, video, { caption: `New support request from @${msg.from.username || msg.from.first_name} (ID: ${userId})\n\n${caption}` }); } else { // If the message type is unsupported bot.sendMessage(msg.chat.id, "Sorry, this type of message is not supported."); } // Confirm to the user that their message has been sent bot.sendMessage(chatId, "Your message has been sent. The administrator will contact you soon."); // Remove the user from the list of those composing a support message delete awaitingSupportMessage[userId]; } }); Deployment on a Server For our bot to operate continuously, we must upload and run it on a server. For deployment, we will use Hostman cloud servers. Uploading to GitHub Before launching the bot on the server, you first need to upload the project files to GitHub. Run the following commands in the console in sequence: Add all changes in the current directory to the next commit: git add . Create a commit with the message "first commit", recording all changes added with git add: git commit -m "first commit" Push the changes to GitHub: git push Server Setup Go to your Hostman control panel and: Create a New Project (optional): Specify an icon, a name, a description, and add users if necessary. Create a Cloud Server: Either from your project or from the Cloud servers page start creating a new cloud server. Select the Region: Choose the region that is closest to you or where the lowest ping is available. Go to the Marketplace tab in the second step and select Node.js. Set the Ubuntu version to the latest one. This ensures that Node.js will already be installed on the server when it starts, so you won’t need to install it manually. Choose Configuration: Select the configuration according to your needs. For running the project, the minimum configuration is sufficient. If the project requires more resources in the future, you can upgrade the server without disrupting its operation. Network Settings: Ensure that you assign a public IP for the server. Configure any additional services as needed. Authorization and Cloud-init: In the Authorization step, you can add your SSH key to the server. However, it’s optional, and you can leave these settings as they are. Server Information: Provide the server’s name and description, and select the project to which you want to add the server. Once everything is set up, click the Order button. After a short while, the server will be up and running, and you can proceed with the next steps. Launching the Bot After creating the server, go to the Dashboard tab, copy the Root password, and open the Console tab. Enter the username root and press Enter. Next, paste the password you copied and press Enter again. When typing or pasting the password, it will not be visible! If everything is correct, you will see a welcome message. Now, run the following command to get the latest updates: sudo apt-get update Create a new folder where you will place the bot. Enter these commands in sequence: cd /sudo mkdir Botcd Bot You can replace the folder name "Bot" with any other name you choose. To ensure Git is installed on the server (it is usually pre-installed by default), check the version using: git --version Next, set up global Git settings to link it to your GitHub profile: git config --global user.name "your GitHub username"git config --global user.email "email used during registration" After this, clone the repository by entering the following command with your repository URL: git clone https://github.com/username/School-Quiz During cloning, you will be prompted to enter your username and then your password. If you have two-factor authentication (2FA) enabled on your GitHub account, entering your regular password will result in an error saying the password is incorrect. To clone a repository with 2FA enabled, you need to create a personal access token. Click your profile picture in the top-right corner and select “Settings”. In the left-hand menu, click “Developer settings”. Under the “Personal access tokens” section, select “Tokens (classic)” and click “Generate new token”. Set token parameters: In the “Note” field, provide a description for the token. Set the expiration date for the token in the “Expiration” field. Under “Select scopes”, choose the necessary permissions for the token. For example, to work with repositories, select repo. Click “Generate token”. Copy the generated token and store it in a secure place. Note that you won’t be able to view the token again after closing the page. Once you have the personal access token, use it instead of your password when prompted during the repository cloning process. Navigate to your project folder using the following command: cd School-Quiz Replace School-Quiz with the actual name of your project. To install the project dependencies, run: npm install Once the packages are installed, you can start the project by running: npm start In the console, you should see the message “Bot is running”. However, there is one issue—if you restart the server or close the console, the bot will stop working! To ensure the bot runs continuously and automatically starts after a server reboot, you need to install a process manager like pm2. Install pm2 globally using the following command: sudo npm install pm2 -g Next, start the Node.js server using pm2: sudo pm2 start index.js --name "bot-quiz" --watch In this example, the process is named bot-quiz, but you can use any name you prefer. Set up automatic startup on server reboot: sudo pm2 startup Save all the changes made: sudo pm2 save Conclusion In this guide, we covered the entire process of creating a Telegram bot using Node.js, from registering the bot via BotFather to deploying the finished solution on a server.