Greeting Bot

Build a bot that welcomes each user once, says hello, repeats what you send and lists its commands.

Level: Beginner · Tags: WhatsApp, Telegram, Commands

Features shown: WELCOME trigger · text and regex triggers · ctx.pass() · slash commands · catch-all · terminal simulator

Prerequisites

Node.js 22.12 or newer and a folder with "type": "module" (see Getting started). Then install:

npm install @botmesh/core @botmesh/baileys

The complete bot

// bot.js
import { Bot, WELCOME, defineBot, isMainModule, slashCommandsPlugin } from '@botmesh/core'
import { BaileysProvider } from '@botmesh/baileys'

const HELP = [
  '🤖 *What I can do*',
  '• hi: say hello',
  '• echo <text>: I repeat your text',
  '• /id: your id · /ping: am I alive?',
].join('\n')

const createBot = defineBot((provider) => {
  const bot = new Bot({ provider })

  // /start /help /reset /cancel /id /ping; /start and /help answer with HELP
  bot.plug(slashCommandsPlugin, { greeting: HELP })

  // First contact only: greet once per user, then let the message go on
  bot.when(WELCOME, async (ctx) => {
    await ctx.reply(`🎉 Welcome to the demo bot, ${ctx.pushName ?? 'friend'}!`)
    ctx.pass()
  })

  // Whole-message match, case and accents ignored
  bot.when(['hi', 'hello', 'hey'], (ctx) =>
    ctx.reply(`👋 Hi ${ctx.pushName ?? 'there'}! Send /help to see what I can do.`),
  )

  // A regex trigger: everything after "echo"
  bot.when(/^echo\s+/i, (ctx) => ctx.reply(`🔁 ${ctx.body.replace(/^echo\s+/i, '')}`))

  // Runs only when nothing above handled the message
  bot.onMessage((ctx) => ctx.reply('🤔 I did not get that. Send /help.'))

  return bot
})

export default createBot

// `node bot.js` connects to WhatsApp; `npx botmesh dev bot.js` skips this block
if (isMainModule(import.meta)) {
  const bot = await createBot(new BaileysProvider({ session: 'greeting-bot' }))
  bot.on('ready', () => console.log('✅ Connected. Send "hi" from another phone.'))
  await bot.start()
}

Sample transcript

Captured with npx botmesh dev bot.js --name Ana:

user › Hí
bot › 🎉 Welcome to the demo bot, Ana!
bot › 👋 Hi Ana! Send /help to see what I can do.
user › echo Good morning!
bot › 🔁 Good morning!
user › /help
bot › 🤖 *What I can do*
      • hi: say hello
      • echo <text>: I repeat your text
      • /id: your id · /ping: am I alive?
user › /ping
bot › pong 🏓
user › what's up?
bot › 🤔 I did not get that. Send /help.

How it works

• WELCOME fires on the first message of each user (per chat in a DM, per participant in a group) and runs before every other trigger. ctx.pass() lets the same message continue, so “Hí” also reaches the hi handler. /reset re-arms the welcome.
• Text triggers compare the whole message after normalizing it (lowercase, accents stripped, spaces collapsed): 'hi' matches “Hí ” but not “hi there”. A list matches any of its entries.
• A regex matches anywhere in the text; ctx.body keeps the original text, so the echo keeps the user’s casing.
• slashCommandsPlugin adds /start, /help, /reset, /cancel, /id and /ping; greeting replaces the text of /start and /help.
• bot.onMessage() is the catch-all: it only runs when nothing else handled the message.

Run it on WhatsApp or Telegram

node bot.js prints a QR: scan it in WhatsApp → Linked devices. For Telegram, install @botmesh/telegram and swap the provider as shown in Or connect Telegram; the factory does not change.

Next steps

• FAQ bot: more trigger forms (contains, regex, lists)
• Special triggers: WELCOME, message types and calls
• Testing: assert these replies with createTestBot