Hey there! As someone new to building Telegram Bots with Node.js, I’ll walk you through a concrete, beginner-friendly implementation to save chat IDs to a database and send bulk notifications. Let’s dive in!

First, initialize a new Node.js project and install the two key packages we’ll need:

• node-telegram-bot-api: The go-to library for interacting with Telegram’s Bot API
• sqlite3: A lightweight, file-based SQL database (perfect for beginners since it doesn’t require a separate server)

Run these commands in your terminal:

npm init -y
npm install node-telegram-bot-api sqlite3

Create a file (like bot.js) and add this code to set up your bot and connect to the database. Don’t forget to replace YOUR_TELEGRAM_BOT_TOKEN with the token you got from @BotFather!

const TelegramBot = require('node-telegram-bot-api');
const sqlite3 = require('sqlite3').verbose();

// Replace with your actual bot token from @BotFather
const token = 'YOUR_TELEGRAM_BOT_TOKEN';
const bot = new TelegramBot(token, { polling: true }); // Polling mode is great for development

// Connect to SQLite database (creates the file if it doesn't exist)
const db = new sqlite3.Database('chat_ids.db', (err) => {
  if (err) {
    console.error('Database connection error:', err.message);
  } else {
    console.log('Successfully connected to the chat IDs database!');
  }
});

// Create a table to store chat IDs (only if it doesn't exist already)
db.run(`CREATE TABLE IF NOT EXISTS chats (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  chat_id TEXT UNIQUE NOT NULL
)`);

Let’s add a /start command so users can subscribe to notifications. When they send this command, we’ll save their chat ID to the database (and avoid duplicates with INSERT OR IGNORE):

bot.onText(/\/start/, (msg) => {
  const chatId = msg.chat.id.toString();
  
  // Insert the chat ID, ignore if it's already in the database
  db.run(`INSERT OR IGNORE INTO chats (chat_id) VALUES (?)`, [chatId], function(err) {
    if (err) {
      return console.error('Error saving chat ID:', err.message);
    }
    
    if (this.changes > 0) {
      bot.sendMessage(chatId, '🎉 You\'ve subscribed to notifications! You\'ll get updates from now on.');
    } else {
      bot.sendMessage(chatId, 'ℹ️ You\'re already subscribed to notifications.');
    }
  });
});

Now let’s build a function to fetch all saved chat IDs and send a message to each one. We’ll also add a /sendnotification command so you can test this easily:

// Function to send a notification to all subscribed users
function sendBulkNotification(message) {
  db.all(`SELECT chat_id FROM chats`, (err, rows) => {
    if (err) {
      return console.error('Error fetching chat IDs:', err.message);
    }
    
    rows.forEach((row) => {
      const targetChatId = row.chat_id;
      bot.sendMessage(targetChatId, message)
        .catch((err) => {
          // Handle cases where the bot can't send a message (e.g., user blocked the bot)
          console.log(`Failed to send to ${targetChatId}: ${err.message}`);
          // Optional: Remove invalid chat IDs from the database to clean up
          // db.run(`DELETE FROM chats WHERE chat_id = ?`, [targetChatId]);
        });
    });
  });
}

// Test the notification system with a command
bot.onText(/\/sendnotification (.+)/, (msg, match) => {
  const notificationText = match[1]; // Capture the message after the command
  sendBulkNotification(notificationText);
  bot.sendMessage(msg.chat.id, '✅ Notification sent to all subscribed users!');
});

Let’s make it user-friendly by adding an /unsubscribe command so users can opt out:

bot.onText(/\/unsubscribe/, (msg) => {
  const chatId = msg.chat.id.toString();
  
  db.run(`DELETE FROM chats WHERE chat_id = ?`, [chatId], function(err) {
    if (err) {
      return console.error('Error unsubscribing:', err.message);
    }
    
    if (this.changes > 0) {
      bot.sendMessage(chatId, '👋 You\'ve unsubscribed from notifications. We\'ll miss you!');
    } else {
      bot.sendMessage(chatId, 'ℹ️ You weren\'t subscribed to notifications anyway.');
    }
  });
});

• Polling vs Webhooks: We used polling mode here because it’s easier to set up for development. For production, switch to webhooks for better performance (you’ll need a public URL for that).
• Database Choice: SQLite is perfect for small-scale bots. If you need to scale later, you can swap it for PostgreSQL or MongoDB—just adjust the database query syntax.
• Error Handling: Always handle errors (like failed message sends) to keep your bot running smoothly.

内容的提问来源于stack exchange，提问作者totalnewb