Ways a Discord Bot Can Respond to Commands

This is a continuation of Building a Hello World Discord Bot. You can also see the video version at https://www.youtube.com/watch?v=VgWloMi6OHY

Now that you have a basic bot built, we’ll want to explore the different ways you can respond using the bot.

Direct Messages

Bots will parse any message they have access to, this actually includes direct messages to the bot itself. If you want to setup direct messages, you’ll actually need the bot to message you first. In this example, we’ll use the command !dm to get the bot to message you to start. Add the following code into your message handler.

      if(msg.content.startsWith("!dm")) {
        let messageContent = msg.content.replace("!dm", "")
        msg.member.send(messageContent)
      }

Your index.js should look like this now;

    // Import discord.js and create the client
    const Discord = require('discord.js')
    const client = new Discord.Client();

    // Register an event so that when the bot is ready, it will log a messsage to the terminal
    client.on('ready', () => {
      console.log(`Logged in as ${client.user.tag}!`);
    })

    // Register an event to handle incoming messages
    client.on('message', async msg => {
      // This block will prevent the bot from responding to itself and other bots
      if(msg.author.bot) {
        return
      }

      // Check if the message starts with '!hello' and respond with 'world!' if it does.
      if(msg.content.startsWith("!hello")) {
        msg.reply("world!")
      }

      if(msg.content.startsWith("!dm")) {
        let messageContent = msg.content.replace("!dm", "")
        msg.member.send(messageContent)
      }

    })

    // client.login logs the bot in and sets it up for use. You'll enter your token here.
    client.login('your_token_here');

Start your bot if it isn’t already (or restart it), and issue the !dm command we just added. You should receive a direct message from the bot.

Any command we’ve setup the bot to handle so far can now be issued using the new chat. If you’re coming from my last post, you can issue the !hello command and it should respond in the chat.

Processing Arguments

So far, we’ve been using very basic commands to get our bot to respond, but you can also parse out the entire content of the message sent and handle it differently based on the full input. Let’s add some additional code to parse the message to respond differently, even if the command prefix is the same.

      if (msg.content.startsWith("!args")) {
        const args = msg.content.split(' ')
        let messageContent = ""
        if (args.includes("foo")) {
          messageContent += "bar "
        }
        if (args.includes("bar")) {
          messageContent += "baz "
        }
        if (args.includes("baz")) {
          messageContent += "foo "
        }
        msg.reply(messageContent)
      }

Now if we issue the !args command with a different message to follow, our bot will respond in different ways.

This is how many bots actually work. The bots are coded to use a common prefix (I.e.; !args) and perform different actions based on the content of the message they receive.