Telegram Bot on Cloudflare Workers

A minimal example of a Telegram Bot running on a Cloudflare Worker.

Setup:

1. Get your new bot token from @BotFather: https://core.telegram.org/bots#6-botfather
2. Sign up to Cloudflare Workers: https://workers.cloudflare.com/
3. In the Cloudflare Dashboard go to "Workers" and then click "Create a Service"
4. Choose a name and click "Create a Service" to create the worker
5. Click on "Quick Edit" to change the source code of your new worker
6. Copy and paste the code from bot.js into the editor
7. Replace the TOKEN variable in the code with your token from @BotFather
8. Optional: Change the WEBHOOK variable to a different path and the SECRET variable to a random secret. See https://core.telegram.org/bots/api#setwebhook
9. Click on "Save and Deploy"
10. In the middle panel append /registerWebhook to the url. For example: https://my-worker-123.username.workers.dev/registerWebhook
11. Click "Send". In the right panel should appear Ok. If 401 Unauthorized appears, you may have used a wrong bot token.
12. That's it, now you can send a text message to your Telegram bot

Bot behaviour

The bot will send the original message back with Echo: prepended. If you want to change it, look at the function onMessage(). It receives a Message object and sends a text back:

/**
 * Handle incoming Message
 * https://core.telegram.org/bots/api#message
 */
function onMessage (message) {
  return sendPlainText(message.chat.id, 'Echo:\n' + message.text)
}

The file bot2.js contains an improved bot, that demonstrates how to react to commands, send and receive inline buttons, and create MarkdownV2-formatted text.

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