Log deleted and edited messages with a Discord bot, in discord.py and discord.js

import os

import discord
from discord.ext import commands

LOG_CHANNEL_ID = 123456789012345678  # a channel only staff can see

intents = discord.Intents.default()
intents.message_content = True  # the Message Content intent: switch it on in the Developer Portal too

bot = commands.Bot(command_prefix="!", intents=intents)

def log_channel(guild_id: int | None) -> discord.TextChannel | None:
    channel = bot.get_channel(LOG_CHANNEL_ID)
    return channel if channel and channel.guild.id == guild_id else None

@bot.event
async def on_raw_message_delete(payload: discord.RawMessageDeleteEvent):
    log = log_channel(payload.guild_id)
    message = payload.cached_message
    if log is None or payload.channel_id == log.id or (message and message.author.bot):
        return
    embed = discord.Embed(title="Message deleted", colour=discord.Colour.red())
    embed.add_field(name="Channel", value=f"<#{payload.channel_id}>")
    if message is None:
        embed.description = "Sent before the bot started, or too long ago: its text is not known."
    else:
        embed.add_field(name="Author", value=message.author.mention)
        embed.description = message.content[:4000] or "(no text)"
    await log.send(embed=embed)

@bot.event
async def on_raw_message_edit(payload: discord.RawMessageUpdateEvent):
    log = log_channel(payload.guild_id)
    after, before = payload.message, payload.cached_message
    if log is None or payload.channel_id == log.id or after.author.bot:
        return
    if after.edited_at is None:
        return  # a link preview loading, not an edit
    if before is not None and before.content == after.content:
        return
    embed = discord.Embed(title="Message edited", url=after.jump_url, colour=discord.Colour.orange())
    embed.add_field(name="Author", value=after.author.mention)
    embed.add_field(name="Before", value=(before.content[:1024] or "(no text)") if before else "(not known)", inline=False)
    embed.add_field(name="After", value=after.content[:1024] or "(no text)", inline=False)
    await log.send(embed=embed)

bot.run(os.environ["BOT_TOKEN"])

const { Client, Colors, EmbedBuilder, Events, GatewayIntentBits, Partials } = require("discord.js");

const LOG_CHANNEL_ID = "123456789012345678"; // a channel only staff can see

const client = new Client({
  // MessageContent is privileged: switch it on in the Developer Portal too.
  intents: [GatewayIntentBits.Guilds, GatewayIntentBits.GuildMessages, GatewayIntentBits.MessageContent],
  partials: [Partials.Message], // deletes and edits of messages the bot never had in memory
});

function logChannel(guild) {
  const channel = guild?.channels.cache.get(LOG_CHANNEL_ID);
  return channel?.isTextBased() ? channel : null;
}

client.on(Events.MessageDelete, async (message) => {
  const log = logChannel(message.guild);
  if (!log || message.channelId === log.id || message.author?.bot) return;
  const embed = new EmbedBuilder().setTitle("Message deleted").setColor(Colors.Red)
    .addFields({ name: "Channel", value: `${message.channel}`, inline: true });
  if (message.partial) {
    embed.setDescription("Sent before the bot started, or too long ago: its text is not known.");
  } else {
    embed.addFields({ name: "Author", value: `${message.author}`, inline: true })
      .setDescription(message.content.slice(0, 4000) || "(no text)");
  }
  await log.send({ embeds: [embed] });
});

client.on(Events.MessageUpdate, async (before, after) => {
  const log = logChannel(after.guild);
  if (!log || after.channelId === log.id || after.author?.bot) return;
  if (!after.editedTimestamp) return; // a link preview loading, not an edit
  if (!before.partial && before.content === after.content) return;
  const embed = new EmbedBuilder().setTitle("Message edited").setURL(after.url).setColor(Colors.Orange)
    .addFields(
      { name: "Author", value: `${after.author}` },
      { name: "Before", value: before.partial ? "(not known)" : before.content.slice(0, 1024) || "(no text)" },
      { name: "After", value: after.content.slice(0, 1024) || "(no text)" },
    );
  await log.send({ embeds: [embed] });
});

client.login(process.env.BOT_TOKEN);