Auto-Delete Telegram Bot Messages with Cloudflare Workers
Preface
Set up a keyword-reply bot in a group. There are tons of projects on Github. Skipping that.
But there was never a feature to auto-delete reply messages after a delay.
In my understanding, a worker only runs when an HTTP request comes in, meaning it only runs when someone sends a message in the group. So naturally, it couldn't handle delayed message deletion.
Inspiration
Today I had a sudden idea and asked the AI, "How to implement scheduled tasks with cloudflare workers?"
WOKAO, turns out Cron Trigger has been officially supported since 2022
Then came the boring GPT-oriented development
The pasted code is a telegram bot based on cloudflare worker.
I want to implement a feature to delete the bot's reply messages after a delay of 5~10 minutes.
I bound a KV to this worker: BOT_MSG, used to save the data of sent messages.
I set a cron trigger for this worker to run every 5 minutes.
Please improve this code
Let me paste the code here.
const TOKEN = 'your_bot_token'
const WEBHOOK = '/endpoint'
const SECRET = 'you_should_generate_random_string'
const DELETE_AFTER_MS = 5 * 60 * 1000 // 5 minutes
/**
* Store sent messages into KV
* key: msg:{delete_at}:{chat_id}:{message_id}
*/
async function saveMessage(env, chatId, messageId) {
const deleteAt = String(Date.now() + DELETE_AFTER_MS).padStart(16, '0')
const key = `msg:${deleteAt}:${chatId}:${messageId}`
await env.BOT_MSG.put(key, '1', {
expirationTtl: 20 * 60 // 20 minutes fallback cleanup
})
}
/**
* Cron trigger: delete all expired messages
*/
async function handleScheduled(env) {
const now = Date.now()
const { keys } = await env.BOT_MSG.list({ prefix: 'msg:' })
for (const { name } of keys) {
// key format: msg:{delete_at}:{chat_id}:{message_id}
const [, deleteAt, chatId, messageId] = name.split(':')
if (parseInt(deleteAt) <= now) {
await deleteMessage(chatId, messageId)
await env.BOT_MSG.delete(name)
}
}
}
/**
* Call Telegram API to delete a message
*/
async function deleteMessage(chatId, messageId) {
return (await fetch(apiUrl('deleteMessage', {
chat_id: chatId,
message_id: messageId
}))).json()
}
// ─── Export ────
export default {
async fetch(request, env, ctx) {
const url = new URL(request.url)
if (url.pathname === WEBHOOK) {
return handleWebhook(request, env)
} else if (url.pathname === '/registerWebhook') {
return registerWebhook(url, WEBHOOK, SECRET)
} else if (url.pathname === '/unRegisterWebhook') {
return unRegisterWebhook()
} else {
return new Response('No handler for this request')
}
},
async scheduled(event, env, ctx) {
ctx.waitUntil(handleScheduled(env))
}
}
// ─── Webhook ────
async function handleWebhook(request, env) {
if (request.headers.get('X-Telegram-Bot-Api-Secret-Token') !== SECRET) {
return new Response('Unauthorized', { status: 403 })
}
const update = await request.json()
await onUpdate(update, env)
return new Response('Ok')
}
async function onUpdate(update, env) {
if ('message' in update) {
await onMessage(update.message, env)
}
}
// ─── Message Handler ────
async function onMessage(message, env) {
const text = message.text.toLowerCase();
const originalText = message.text;
// Detect English keywords
const hasHappy = text.includes('happy');
const hasNew = text.includes('new');
const hasYear = text.includes('year');
if (hasHappy && hasNew && hasYear) {
const result = await sendPlainText(message.chat.id, 'Happy New Year to you, too! 🎁', message.message_id);
if (result?.ok && result?.result?.message_id) {
await saveMessage(env, message.chat.id, result.result.message_id)
}
return;
}
// Detect Chinese keywords
const has新 = originalText.includes('新');
const has年 = originalText.includes('年');
const has快 = originalText.includes('快');
const has乐 = originalText.includes('乐');
if (has新 && has年 && has快 && has乐) {
const result = await sendPlainText(message.chat.id, '也祝你新年快乐! 🧧', message.message_id);
if (result?.ok && result?.result?.message_id) {
await saveMessage(env, message.chat.id, result.result.message_id)
}
return;
}
// 233 group's script keyword
const has脚本 = originalText.includes('脚本');
if (has脚本) {
const replyText = `
安装 sing-box 脚本 (第一次运行默认就安装 Reality 协议):
bash <(wget -qO- -o- https://github.com/233boy/sing-box/raw/main/install.sh)安装 Xray 脚本 (第一次运行默认就安装 Reality 协议):
bash <(wget -qO- -o- https://github.com/233boy/Xray/raw/main/install.sh)安装 V2Ray 脚本 (不要用 第一次运行默认装出来的 VMESS+TCP):
bash <(wget -qO- -o- https://github.com/233boy/v2ray/raw/master/install.sh)
`;
const result = await sendPlainText(message.chat.id, replyText, message.message_id);
if (result?.ok && result?.result?.message_id) {
await saveMessage(env, message.chat.id, result.result.message_id)
}
return;
}
}
// ─── Telegram API Helpers ────
async function sendPlainText(chatId, text, replyToMessageId = null) {
return (await fetch(apiUrl('sendMessage', {
chat_id: chatId,
text,
reply_to_message_id: replyToMessageId,
parse_mode: 'HTML'
}))).json()
}
async function registerWebhook(requestUrl, suffix, secret) {
const webhookUrl = `${requestUrl.protocol}//${requestUrl.hostname}${suffix}`
const r = await (await fetch(apiUrl('setWebhook', { url: webhookUrl, secret_token: secret }))).json()
return new Response('ok' in r && r.ok ? 'Ok' : JSON.stringify(r, null, 2))
}
async function unRegisterWebhook() {
const r = await (await fetch(apiUrl('setWebhook', { url: '' }))).json()
return new Response('ok' in r && r.ok ? 'Ok' : JSON.stringify(r, null, 2))
}
function apiUrl(methodName, params = null) {
let query = ''
if (params) {
query = '?' + new URLSearchParams(params).toString()
}
return `https://api.telegram.org/bot${TOKEN}/${methodName}${query}`
}
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Postscript
The GPT used this time is
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