Simple, complete example of a bot in Discord.js

readme.md

The Perfect Lil' Bot

This bot example is the combined work of members of the Discord.js and Idiot Guide's community. It attempts to provide a "complete" starter example of a simple, one-file bot, with comments and information to properly understand each part and how it works.

I believe I should note that I'm a #speedwhore and the lines used in this example are the fastest in terms of performance, especially using Node 8. Though maybe "indexOf" might look ugly for example, it is faster than startsWith by an order of magnitude. I have the performance tests to prove it.

There is also an upcoming example of a more complete bot with separate command files (command handler) as well as per-server configurations. You can find it at: [to be done!]

If what you need is a selfbot, this won't do. I suggest taking a look at evie.selfbot

Setup

• Create a new folder somewhere, give it a bot name, aka MyBot or SuperBot
• Create a file called app.js, and paste in the contents of app.js below.
• Create a file called config.json and give it the following content, using your real bot token:

{ "token"  : "MTg-this-IzNzU3OTA5NjA-is.not-DCeFB-a.real-r4DQlO-t0ken-qerT0",
  "prefix" : "+"
}

You then need to run a couple of things to make this work. Those things are run in console, which can be opened by using SHIFT+Right-Click in your folder, and selected Open command prompt here (your version of windows might say "PowerShell", don't worry it'll work fine!). In console, use the following commands:

npm install discord.js
node app.js

If you've done things right, that should start the bot.

Credits

Project created and maintained with the help of:

• eslachance#4611 , aka 〈evie.codes〉, for the heavy lifting
• York#2400 , for pointing out mistakes, moral support and jester entertainment.
• TrueBoxGuy#3692 for letting me know of a dumb thing I forgot, and an unfinished comment.

app.js

// Load up the discord.js library
const Discord = require("discord.js");

// This is your client. Some people call it `bot`, some people call it `self`, 
// some might call it `cootchie`. Either way, when you see `client.something`, or `bot.something`,
// this is what we're refering to. Your client.
const client = new Discord.Client();

// Here we load the config.json file that contains our token and our prefix values. 
const config = require("./config.json");
// config.token contains the bot's token
// config.prefix contains the message prefix.

client.on("ready", () => {
  // This event will run if the bot starts, and logs in, successfully.
  console.log(`Bot has started, with ${client.users.size} users, in ${client.channels.size} channels of ${client.guilds.size} guilds.`); 
  // Example of changing the bot's playing game to something useful. `client.user` is what the
  // docs refer to as the "ClientUser".
  client.user.setGame(`on ${client.guilds.size} servers`);
});

client.on("guildCreate", guild => {
  // This event triggers when the bot joins a guild.
  console.log(`New guild joined: ${guild.name} (id: ${guild.id}). This guild has ${guild.memberCount} members!`);
  client.user.setGame(`on ${client.guilds.size} servers`);
});

client.on("guildDelete", guild => {
  // this event triggers when the bot is removed from a guild.
  console.log(`I have been removed from: ${guild.name} (id: ${guild.id})`);
  client.user.setGame(`on ${client.guilds.size} servers`);
});


client.on("message", async message => {
  // This event will run on every single message received, from any channel or DM.
  
  // It's good practice to ignore other bots. This also makes your bot ignore itself
  // and not get into a spam loop (we call that "botception").
  if(message.author.bot) return;
  
  // Also good practice to ignore any message that does not start with our prefix, 
  // which is set in the configuration file.
  if(message.content.indexOf(config.prefix) !== 0) return;
  
  // Here we separate our "command" name, and our "arguments" for the command. 
  // e.g. if we have the message "+say Is this the real life?" , we'll get the following:
  // command = say
  // args = ["Is", "this", "the", "real", "life?"]
  const args = message.content.slice(config.prefix.length).trim().split(/ +/g);
  const command = args.shift().toLowerCase();
  
  // Let's go with a few common example commands! Feel free to delete or change those.
  
  if(command === "ping") {
    // Calculates ping between sending a message and editing it, giving a nice round-trip latency.
    // The second ping is an average latency between the bot and the websocket server (one-way, not round-trip)
    const m = await message.channel.send("Ping?");
    m.edit(`Pong! Latency is ${m.createdTimestamp - message.createdTimestamp}ms. API Latency is ${Math.round(client.ping)}ms`);
  }
  
  if(command === "say") {
    // makes the bot say something and delete the message. As an example, it's open to anyone to use. 
    // To get the "message" itself we join the `args` back into a string with spaces: 
    const sayMessage = args.join(" ");
    // Then we delete the command message (sneaky, right?). The catch just ignores the error with a cute smiley thing.
    message.delete().catch(O_o=>{}); 
    // And we get the bot to say the thing: 
    message.channel.send(sayMessage);
  }
  
  if(command === "kick") {
    // This command must be limited to mods and admins. In this example we just hardcode the role names.
    // Please read on Array.some() to understand this bit: 
    // https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/some?
    if(!message.member.roles.some(r=>["Administrator", "Moderator"].includes(r.name)) )
      return message.reply("Sorry, you don't have permissions to use this!");
    
    // Let's first check if we have a member and if we can kick them!
    // message.mentions.members is a collection of people that have been mentioned, as GuildMembers.
    let member = message.mentions.members.first();
    if(!member)
      return message.reply("Please mention a valid member of this server");
    if(!member.kickable) 
      return message.reply("I cannot kick this user! Do they have a higher role? Do I have kick permissions?");
    
    // slice(1) removes the first part, which here should be the user mention!
    let reason = args.slice(1).join(' ');
    if(!reason)
      return message.reply("Please indicate a reason for the kick!");
    
    // Now, time for a swift kick in the nuts!
    await member.kick(reason)
      .catch(error => message.reply(`Sorry ${message.author} I couldn't kick because of : ${error}`));
    message.reply(`${member.user.tag} has been kicked by ${message.author.tag} because: ${reason}`);

  }
  
  if(command === "ban") {
    // Most of this command is identical to kick, except that here we'll only let admins do it.
    // In the real world mods could ban too, but this is just an example, right? ;)
    if(!message.member.roles.some(r=>["Administrator"].includes(r.name)) )
      return message.reply("Sorry, you don't have permissions to use this!");
    
    let member = message.mentions.members.first();
    if(!member)
      return message.reply("Please mention a valid member of this server");
    if(!member.bannable) 
      return message.reply("I cannot ban this user! Do they have a higher role? Do I have ban permissions?");

    let reason = args.slice(1).join(' ');
    if(!reason)
      return message.reply("Please indicate a reason for the ban!");
    
    await member.ban(reason)
      .catch(error => message.reply(`Sorry ${message.author} I couldn't ban because of : ${error}`));
    message.reply(`${member.user.tag} has been banned by ${message.author.tag} because: ${reason}`);
  }
  
  if(command === "purge") {
    // This command removes all messages from all users in the channel, up to 100.
    
    // get the delete count, as an actual number.
    const deleteCount = parseInt(args[0], 10);
    
    // Ooooh nice, combined conditions. <3
    if(!deleteCount || deleteCount < 2 || deleteCount > 100)
      return message.reply("Please provide a number between 2 and 100 for the number of messages to delete");
    
    // So we get our messages, and delete them. Simple enough, right?
    const fetched = await message.channel.fetchMessages({count: deleteCount});
    message.channel.bulkDelete(fetched)
      .catch(error => message.reply(`Couldn't delete messages because of: ${error}`));
  }
});

client.login(config.token);