Making a Basic Bot

Create Application

First, you need to create a bot in Discord's Developer Applications page. Head to Applications Page (opens new window) and hit New Application button. A modal will appear asking you for name, enter the bot name you want and hit Create!

Navigate to Bot tab on left-pane, then click on Add Bot. It will ask you for confirmation, just click on Yes, do it!

Aaand your bot now has a life! Yes, a life! It has successfully become a Discord User. Now you can go ahead and invite the bot to your server. Now navigate to OAuth2 tab and scroll down a bit; then select bot scope. And optionally, below there you can select permissions to give to bot!

Copy the link from there and paste in a new tab, select server and Authorize! Bot will be in your own server!

Uh oh- bot is offline!? Don't worry! We'll wake up this bot!

Get Bot's Token

What's a token? It acts like a password for bots to login! Never share this to anyone! Anyone!

On the Bot page itself, there is a Copy Token button - go ahead and click on it! Token will be on your clipboard. Alternatively, you can Click to Reveal Token.

WARNING

Token should NEVER be shared with ANYONE! Token gives complete, yes complete access over bot and can destroy it badly.

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In case you really lost it, best way is to reset it using Regenerate button on the same page, this will invalidate any previous token.

Write Code

Let's actually start writing code! If you still haven't done your setup, it's easy! Just head to Setup section.

Assuming you have a deps.ts file in your project directory, go ahead and make a mod.ts file (bot.ts or any other name would work too!)

// Importing Client and Intents class from Harmony
import { Client, Intents } from './deps.ts'

// Creating client (or bot!)
const client = new Client()

// Listen for when bot is connected to Discord (i.e. logged in)
client.on('ready', () => {
    console.log('Ready!')
})

// Proceed with connecting to Discord (login)
client.connect('super secret token comes here', Intents.None)

Pretty simple! Try running deno run --allow-net mod.ts (replace mod.ts with your file name if not same). Aaaand you'll see your bot online! That's pretty cool - but uh bot does nothing! Let's add a simple ping-pong command.

It's worth noticing that we're putting client.connect at end because we're adding listeners to our client, to make sure bot doesn't login before listening to events. Weird case though!

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Haven't code deps.ts till now? here's the code (again)

export * from 'https://deno.land/x/[email protected]/mod.ts'

Ping-Pong!

Let's proceed with adding a simple command, ping! For that, your bot will listen to a event called messageCreate - which is fired whenever a message is created (i.e. sent).

// Importing required classes from Harmony
import { Client, Intents, Message } from './deps.ts'

// ... rest of the code

// Listen for an event which is fired when a Message is sent
client.on('messageCreate', (message: Message) => {
    // All the message data is inside `Message` here.
    // For now, we just need the text of the Message, that is called `content`.
    // Content of Message can be accessed using `<Message>.content`; here message.content
    // Let's compare that to a string "!ping", and reply back with "Pong!"
    if (message.content == '!ping') {
        message.reply('Pong!')
    }
})

client.connect('super secret token comes here', Intents.None)

Yes! That's it! We got our own ping command. Now try running the bot and send !ping!

Got stuck? This is our resulting code,

import { Client, Intents } from './deps.ts'

const client = new Client()

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

client.on('messageCreate', (message: Message) => {
    if (message.content == '!ping') {
        message.reply('Pong!')
    }
})

// Proceed with connecting to Discord (login)
client.connect('super secret token comes here', Intents.None)

Using Command Client

But that's quite not how Commands actually work! With Harmony, you can create a Client with additional features - such as Commands and Extensions! It's the CommandClient! A built-in framework to make commands very easily.

Let's look into making same command - but with Command Client!

import { CommandClient, Command, Intents, CommandContext } from './deps.ts'

// Initialize our Command Client with prefix "!".
// Fact, you can put multiple prefixes here using array!
// Example: prefix: [ '!', '.' ]
const client = new CommandClient({
    prefix: '!'
})

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

// Make a class extending Command (inheriting everything from Command)
class PingCommand extends Command {
    name = 'ping'
    execute(ctx: CommandContext) {
        ctx.message.reply('Pong!')
    }
}

// Register the Command
client.commands.add(PingCommand)

// Connect the client to Discord
client.connect('token comes here', Intents.None)

This looks cleaner! Moreover, there are many more options to customize commands, such as limiting command to certain users, channels, guilds, or making Command guild only or DM only! A lot more!

Not familiar with classes or just don't like them? Don't worry! You can import CommandBuilder from ./deps.ts and use it like this:

const myCommand = new CommandBuilder()
  .setName("ping")
  .onExecute((ctx: CommandContext) => {
      ctx.message.reply('Pong!')
  })

Command Builder can do everything same as class based commands.

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Read more about classes here (opens new window) and more specifically for TypeScript here (opens new window).