Raw event reaction add example

index.js

const { Client } = require('discord.js');
const client = new Client();

client.on('ready', () => {
	console.log('Ready!');
});

const events = {
	MESSAGE_REACTION_ADD: 'messageReactionAdd',
	MESSAGE_REACTION_REMOVE: 'messageReactionRemove',
};

client.on('raw', async event => {
	// `event.t` is the raw event name
	if (!events.hasOwnProperty(event.t)) return;

	const { d: data } = event;
	const user = client.users.get(data.user_id);
	const channel = client.channels.get(data.channel_id) || await user.createDM();

	// if the message is already in the cache, don't re-emit the event
	if (channel.messages.has(data.message_id)) return;

	// if you're on the master/v12 branch, use `channel.messages.fetch()`
	const message = await channel.fetchMessage(data.message_id);

	// custom emojis reactions are keyed in a `name:ID` format, while unicode emojis are keyed by names
	// if you're on the master/v12 branch, custom emojis reactions are keyed by their ID
	const emojiKey = (data.emoji.id) ? `${data.emoji.name}:${data.emoji.id}` : data.emoji.name;
	const reaction = message.reactions.get(emojiKey);

	client.emit(events[event.t], reaction, user);
});

client.on('messageReactionAdd', (reaction, user) => {
	console.log(`${user.username} reacted with "${reaction.emoji.name}".`);
});

client.on('messageReactionRemove', (reaction, user) => {
    console.log(`${user.username} removed their "${reaction.emoji.name}" reaction.`);
});
client.login('pleasedonthackme');

uncommented.js

const { Client } = require('discord.js');
const client = new Client();

client.on('ready', () => {
	console.log('Ready!');
});

const events = {
	MESSAGE_REACTION_ADD: 'messageReactionAdd',
	MESSAGE_REACTION_REMOVE: 'messageReactionRemove',
};

client.on('raw', async event => {
	if (!events.hasOwnProperty(event.t)) return;

	const { d: data } = event;
	const user = client.users.get(data.user_id);
	const channel = client.channels.get(data.channel_id) || await user.createDM();

	if (channel.messages.has(data.message_id)) return;

	const message = await channel.fetchMessage(data.message_id);
	const emojiKey = (data.emoji.id) ? `${data.emoji.name}:${data.emoji.id}` : data.emoji.name;
	const reaction = message.reactions.get(emojiKey);

	client.emit(events[event.t], reaction, user);
});

client.on('messageReactionAdd', (reaction, user) => {
	console.log(`${user.username} reacted with "${reaction.emoji.name}".`);
});

client.on('messageReactionRemove', (reaction, user) => {
    console.log(`${user.username} removed their "${reaction.emoji.name}" reaction.`);
});
client.login('pleasedonthackme');

@RisedSky This gist was made for discord.js v11, but should no longer be used. Please upgrade to discord.js v12 and use partial structures