Telegram bots are automated applications that run inside Telegram. Users can interact with bots by sending messages, commands, and inline requests. Today, we'll walk you through how to build a simple Telegram bot using Node.js that provides weather and time information for any city.

Prerequisites

Before we start, make sure you have the following:

• Node.js and npm are installed on your machine.

• A Telegram account to create and manage bots.

• An API key from OpenWeatherMap.

Setting Up Your Project

Firstly, install the required Node.js packages: dotenv, node-telegram-bot-api, axios, and moment-timezone.

npm install dotenv node-telegram-bot-api axios moment-timezone

• dotenv: To handle environment variables.

• node-telegram-bot-api: To interact with the Telegram Bot API.

• axios: To make HTTP requests to the OpenWeatherMap API.

• moment-timezone: To handle time and time zones.

Creating the Bot

You'll need a bot token from Telegram. Use the BotFather to create a new bot and get the token. Save the token and your OpenWeatherMap API key in a **.env** file:

TELEGRAM_BOT_TOKEN=your_telegram_bot_token OPENWEATHERMAP_API_KEY=your_openweathermap_api_key

In your main JavaScript(app.js) file, initialize your bot and the storage object:

require('dotenv').config()

const TelegramBot = require('node-telegram-bot-api') const axios = require('axios') const moment = require('moment-timezone')

const TELEGRAM_BOT_TOKEN = process.env.TELEGRAM_BOT_TOKEN const OPENWEATHERMAP_API_KEY = process.env.OPENWEATHERMAP_API_KEY

const bot = new TelegramBot(TELEGRAM_BOT_TOKEN, { polling: true }) const storage = {}

The storage object will keep track of the state of the conversation with each user.

Handling Commands and Callback Queries

Next, handle the /start command and present the user with two options: getting the weather or the time. We use an inline keyboard for this:

bot.onText(/\/start/, (msg) => {
  const chatId = msg.chat.id
  bot.sendMessage(
    chatId,
    'Hello! This bot can show you the weather and time for any city. To use it, please choose an option below:',
    {
      reply_markup: {
        inline_keyboard: [
          [{ text: 'Get Weather', callback_data: 'get_weather' }],
          [{ text: 'Get Time', callback_data: 'get_time' }],
        ],
      },
    }
  )
})

The bot then listens for button presses and asks the user to enter the name of a city:

bot.on('callback_query', async (callbackQuery) => {
  const chatId = callbackQuery.message.chat.id
  const data = callbackQuery.data

  switch (data) {
    case 'get_weather':
      const userDataWeather = getUserData(chatId)
      userDataWeather.waitingForCity = true
      userDataWeather.waitingForWeather = true
      bot.sendMessage(chatId, 'Please enter the name of the city or send /stop to cancel:')
      break
    case 'get_time':
      const userDataTime = getUserData(chatId)
      userDataTime.waitingForCity = true
      userDataTime.waitingForTime = true
      bot.sendMessage(chatId, 'Please enter the name of the city or send /stop to cancel:')
      break
    default:
      break
  }
})

Handling User Responses

The **getUserData** function initializes or retrieves the user's state from the **storage** object:

function getUserData(chatId) {
  let userData = storage[chatId]
  if (!userData) {
    userData = {
      waitingForCity: false,
      waitingForWeather: false,
      waitingForTime: false,
    }
    storage[chatId] = userData
  }
  return userData
}

Then, the bot listens for a message from the user, which should be the city's name:

bot.on('message', async (msg) => {
  const chatId = msg.chat.id
  const text = msg.text

  const userData = getUserData(chatId)
  if (userData && userData.waitingForCity) {
    const city = text
    let messageText = ''
    if (userData.waitingForWeather) {
      messageText = await getWeatherData(city)
    } else if (userData.waitingForTime) {
      messageText = await getTimeData(city)
    }
    bot.sendMessage(chatId, messageText)
    resetUserData(chatId)
  }
})

We reset the user data after sending the response so the bot is ready for the next command. The resetUserData function looks like this:

function resetUserData(chatId) {
  const userData = getUserData(chatId)
  userData.waitingForCity = false
  userData.waitingForWeather = false
  userData.waitingForTime = false
}

Fetching the Weather and Time Data

The getWeatherData function fetches weather data from the OpenWeatherMap API:

async function getWeatherData(city) {
  const response = await axios.get(
    `http://api.openweathermap.org/data/2.5/weather?q=${city}&appid=${OPENWEATHERMAP_API_KEY}`
  )
  const weatherData = response.data
  const weatherDescription = weatherData.weather[0].description
  const temperature = Math.round(weatherData.main.temp - 273.15)
  const messageText = `The weather in ${city} is currently ${weatherDescription} with a temperature of ${temperature}°C.`
  return messageText
}

The getTimeData function gets the current time in the city's local timezone using moment-timezone:

async function getTimeData(city) {
  const response = await axios.get(
    `http://api.geonames.org/timezoneJSON?formatted=true&lat=${city.lat}&lng=${city.lon}&username=demo&style=full`
  )
  const data = response.data
  const localTime = data.time
  const messageText = `The current time in ${city} is ${localTime}.`
  return messageText
}

Running The Bot

Update your package.json file to run the bot:

 "scripts": {
    "start": "node app.js"
  },

Run the command on a terminal:

npm start

Open your Bot on the Telegram app to test it:

Wrapping Up

This simple bot is a fun way to explore the capabilities of Telegram bots and Node.js. The bot could be expanded in numerous ways, such as supporting more commands, integrating more APIs, or adding a more sophisticated conversation state.

Remember to secure your API keys and tokens properly. Never expose them in your code or version control system. Instead, use environment variables or some form of secure secret management.

Happy coding!