What you'll need

• Node.js 16.6.0 or newer is required
• A Discord account
• Basic knowledge of javascript
• Code editor of your choice
• A discord server for testing

Step 1: Creating the bot

Go to Discord Developer Portal and now you have to sign in to create a developer account. Once you did that click on "New Application" button and then give your bot a name, and click "Create"

Once that is done, navigate to the "Bot" page and click on "Add Bot"

Now, a section will appear

Click on "Copy" to copy the token and save it for later

Step 2: Adding the bot to your server

Now, for adding the bot to your server navigate to "OAuth2" and select "Bot" and click on "Copy" at the bottom right corner

After copying the url paste it in the browser. You will be redirected to a page

Just select a server and click on "Authorize" If you follow every step then you will see a offline bot in your server. Let's bring it online

Step 3: Setting up your project

Create a new folder and name it whatever you want and open it in terminal and run the following command:

npm init

Once that is done, let's install required npm packages for this bot

npm install discord.js

Step 4: Coding the bot

Create a index.js file in the project folder

In the index.js we will write a function which print something to in console when bot come online

// index.js
const { Client, Intents } = require('discord.js');
require('dotenv').config();

const client = new Client({ intents: [Intents.FLAGS.GUILDS, Intents.FLAGS.GUILD_MESSAGES] });

client.on('ready', () => {
  console.log(`Logged in as ${client.user.tag}!`);
});

client.login(process.env.TOKEN); // Paste the bot token here

Also, don't forget to create a .env file and paste the bot token we copied earlier

TOKEN='bot token'

Now you just have to run the following command and your bot will be online:

node index.js

Step 5: Creating Commands

Let's start by creating a command which reply with pong, when we type ping

client.on('messageCreate', message => { // This function will run when anyone sends a message in guild
    if (message.content == 'ping') { // reply with pong
         message.channel.send('pong');
    }
    console.log(message.content)
})

Run the index.js file and go to any channel in the guild

Conclusion

You can create more cool things like music bot, moderation bot with discord.js. You can visit discord.js documentation for info