How would I react to a specific message in [discord.js]

Question

I'm trying to make my bot react to a specific message in a channel. This is the code I have so far:

message.fetch(`messageID`).then(message => {
  message.react(`emoji`);
});

Answer 1

To fetch a specific message you must at least fetch it's channel before:

message.client.channels.fetch("channelID").then(channel => {
    channel.messages.fetch("messageID").then(message => {
        message.react("emoji");
    }
}

Answer 2

bot.on('message', message=>{
  message.bot.channels.fetch("channelID").then(channel => {
    channel.messages.fetch("messageID").then(message => {
        message.react(emoji);
    })
  })
});