This is about how to do webhook on deno grammy.

webhook.ts

import { Bot, webhookCallback } from 'https://deno.land/x/grammy@v1.11.0/mod.ts';
import { serve } from 'https://deno.land/std@0.154.0/http/server.ts';
import 'https://deno.land/x/dotenv@v3.2.0/load.ts';

const bot = new Bot(Deno.env.get('BOT_TOKEN')!);
const handleUpdate = webhookCallback(bot, 'std/http');

bot.on('message', (ctx) => ctx.reply('Hi there!'));

serve(async (req) => {
  if (req.method == 'POST') {
    const url = new URL(req.url);
    if (url.pathname.slice(1) == bot.token) {
      try {
        return await handleUpdate(req);
      } catch (err) {
        console.error(err);
      }
    }
  }
  return new Response();
});

Deno.env.get('MODE') === 'development' && bot.start();
Deno.env.get('MODE') === 'production' &&
  bot.api.setWebhook(
    Deno.env.get('WEBHOOK_URL')! + '/' + Deno.env.get('BOT_TOKEN')!
  );

// You need to have BOT_TOKEN, MODE and WEBHOOK_URL environment variables