Reactions and voice

People do more on Discord than write: they react to messages, vote in polls, join voice channels. Each of these is an event too, with its name. This page adds two to your bot, a bookmark that works with a reaction and a greeting in voice, and shows what is different about them: some events come with less than a message does.

A bookmark with a reaction

Create src/events/bookmark.ts:

src/events/bookmark.ts

import { event } from 'chapterjs';

export default event({
  name: 'reactionAdd',
  async run({ reaction: { emoji, member, channel, messageId }, guild }) {
    if (emoji.name !== '🔖') return;
    const link = `https://discord.com/channels/${guild.id}/${channel.id}/${messageId}`;
    await member.send(`You bookmarked a message in #${channel.name}: ${link}`);
  },
});

Save it, then react 🔖 to any message of your test server: the bot sends you its link in private. There was no switch to turn on this time:

↻ Your files now need more from Discord (GUILD_MESSAGE_REACTIONS): reconnecting...

Reactions are not privileged: Discord does not consider them personal, unlike what people write. The function receives the reaction and the server, guild, and takes from the reaction what it needs: emoji, member, channel, messageId. emoji is the emoji of the reaction. For a standard emoji, emoji.name is the character itself ('🔖'); a custom emoji of a server has a name and an id.

Safe by default, again

The rules of the previous page hold here: by default a reaction file runs for people, in servers. The reactions of bots are left out, yours included, so the file never reacts to what it does itself; bots: true lets them in. And because the file listens in servers, guild, and the channel and member of the reaction, are always there, with no ?. to write. where: 'dm' or where: 'both' change that exactly like for messages.

Only an id for the message

Look at what the reaction holds: messageId, not a message. When someone reacts, Discord sends who reacted and with what, but not the message: it may be years old. And your bot remembers no message. So the reaction gives its id, and reaction.message is null. Often the id is enough: the link above is built from it, without asking Discord anything. When you really need the message, ask for it: await channel.fetchMessage(messageId). Do it after the checks, never for every reaction. reactionRemove goes further: Discord sends only the id of who removed their reaction. ChapterJS asks Discord who it is the first time, then remembers them, so reaction.user is always there; reaction.member is only there when the bot remembers that member.

Hello in voice

Create src/events/greeter.ts:

src/events/greeter.ts

import { event } from 'chapterjs';

export default event({
  name: 'voiceJoin',
  async run({ voice: { member, channel } }) {
    await channel.send(`Welcome to ${channel.name}, ${member.displayName}!`);
  },
});

Join a voice channel of your test server: the bot writes in the chat of that channel. Every voice channel has a text chat, and voice.channel is a VoiceChannel you can send to. The function receives voice (who, where, and their voice state) and the server, guild. Discord tells a bot only that “someone’s voice state changed”. ChapterJS remembers who is in which channel, compares, and gives you four events instead of one:

`name`	Runs when
`voiceJoin`	Someone joins a voice channel
`voiceLeave`	Someone leaves, or is disconnected
`voiceMove`	Someone goes from one channel to another
`voiceUpdate`	Someone mutes, deafens, starts a stream or a camera

And the others

Polls (pollVoteAdd), typing (typingStart), bans (banAdd), the audit log, invites, emojis, scheduled events, threads and presences all work the same way: an event() with the name of the event, and what your function receives typed from that name. The Guide has a page for each family.

Points of attention

A reaction gives an id, not a message. Build what you can from the ids; fetch the message only when you need it.
Reactions are frequent. Like for messages, keep the check first and cheap, and return early.
Presences are privileged, and heavy. presenceUpdate needs the Presence Intent and arrives for every change of every member: only add it when your bot really needs it.
Voice greetings can be noisy. Someone reconnecting five times gets greeted five times: keep the message short, or write it only in some channels.

Recap

reactionAdd, reactionRemove, pollVoteAdd, typingStart, the voice events and the others are declared with event(), like memberJoin.
Reactions ignore bots and private messages by default, like messages; bots and where change it.
Every event gives what it is about and guild: reaction, vote, voice… Some only hold ids: reaction.messageId is always there, reaction.message is null; user is asked to Discord once when needed.
Four voice events tell a join, a leave, a move and a change apart.

Playing in voice

Make your bot join a voice channel and play a sound.

Guide: Reactions, polls and typing

The same events, in short.

Start here

Your first bot

Commands

Events

Voice

Components

By itself

Languages

Growing

Testing

Going online