# Useful packages

# Day.js

Day.js is a powerful package that parses, validates, manipulates, and displays dates and times in JavaScript. It allows you to quickly and easily format dates in any way you want or parse strings back into JavaScript Date objects. There are many plugins for it that allow you to work with durations and more.

For example if you wanted to ask your users to give you a date,
you can use Day.js to turn it into a Date object you can use in your code:

const input = await interaction.channel.awaitMessages({ 
	filter: m => m.author.id === interaction.user.id, 
	max: 1,
	time: 10e3,
	errors: ['time'],
});
const date = dayjs(input.first().content).toDate();

Using the duration pluginopen in new window, you could tell the user if the date is in the future or the past:

if (date.isValid()) {
	const now = dayjs();
	const duration = date - now;
	const formatted = dayjs.duration(duration, 'ms').format();

	if (duration > 0) {
		interaction.reply(`The date you gave me is ${formatted} into the future.`);
	} else {
		interaction.reply(`The date you gave me is ${formatted} into the past.`);
	}
} else {
	interaction.reply('You didn\'t give me a valid date.');
}

# ms

Ms is another tool for working with times in JavaScript. However, ms specializes on durations. It allows you to convert times in milliseconds into human-readable formats and vice versa.

Example:

await interaction.reply('Send two messages and I\'ll tell you how far apart you sent them.');
const messages = await interaction.channel.awaitMessages({
	filter: m => m.author.id === interaction.user.id,
	max: 2,
	time: 30e3,
	errors: ['time'],
});

const difference = messages.last().createdTimestamp - messages.first().createdTimestamp;
const formatted = ms(difference);

await interaction.followUp(`You sent the two messages ${formatted} apart.`);

# common-tags

Common-tags is a library all about working with template literals.
So far, you have probably only used them for interpolating variables into your strings, but they can do a whole lot more. If you got time, you should check out the MDN's documentation about tagged literals.open in new window.

Ever got annoyed your multi-line strings had nasty bits of indentation in them, but you did not want to remove the indentation in your source code?
common-tags got you covered:

const packageName = 'common-tags';

if (someCondition) {
	const poem = stripIndents`
		I like ${packageName}.
		It makes my strings so pretty,
		you should use it too.
	`;

	console.log(poem);
}

This will print your little poem like expected, but it will not have any tabs or other whitespace on the left.

But this is just the start! Another set of useful functions are the list-related functions: inlineLists, commaLists, etc.
With those, you can easily interpolate arrays into your strings without them looking ugly:

const options = ['add', 'delete', 'edit'];

// -> Do you want me to add, delete or edit the channel?
interaction.reply(oneLineCommaListsOr`
	Do you want me to ${options} the channel?
`);

Check the the documentation to find more useful functions.

# chalk

Chalk is not exactly useful for Discord bots themselves, but it will make your terminal output a lot prettier and organized. This package lets you color and style your console.logs in many different ways; No more simple white on black.

Let's say you want your error messages to be easily visible; Let us give them a nice red color:

console.error(chalk.redBright('FATAL ERROR'), 'Something really bad happened!');

You can also chain multiple different multipliers.
If you wanted to have green text, a grey background, and have it all underlined, that is possible:

console.log(chalk.green.bgBrightBlack.underline('This is so pretty.'));

# pino

Pino is a Node.js logger with a very low overhead. But why does that even matter, if console.log() exists? Well, console.log() is quite slow and not very versatile. Whenever you make a call to console.log() your program halts and cannot do anything until the logging is finished.

To get started, install the package:

npm install pino@next
npm install -g pino-pretty

yarn add pino@next
yarn global add pino-pretty

pnpm add pino@next
pnpm add --global pino-pretty

Pino is highly configurable, so we heavily recommend you take a look at their documentation yourself.

To use the same logger across the project you can put the following code into it's own file, for example logger.js and import it when needed:

const pino = require('pino');
const logger = pino();
module.exports = logger;

const { Client, Intents } = require('discord.js');
const client = new Client({ intents: [Intents.FLAGS.GUILDS] });
const logger = require('./logger');

client.on('ready', () => logger.info('The bot is online'));
client.on('debug', m => logger.debug(m));
client.on('warn', m => logger.warn(m));
client.on('error', m => logger.error(m));

client.login('your-token-goes-here');

Pino logs in a json format, so other programs and services like log aggrregators can easily parse and work with the output. This is very useful for production systems, but quite tedious to read during development. This is why you installed pino-pretty earlier. Instead of formatting the log output itself the developers recommended that you pipeopen in new window the log output to other services instead. pino-pretty is a formatter you can use for easy-to-read logs during development.

We recommend you set pino-pretty up in a package script in your package.json file, rather than typing the pipeline out every time. Please read our guide section on package scripts, if you are not sure what we're talking about here.

{
	"name": "my-bot",
	"version": "1.0.0",
	"description": "A Discord bot!",
	"main": "index.js",
	"scripts": {
		"test": "echo \"Error: no test specified\" && exit 1",
		"start": "node .",
		"lint": "eslint .",
		"dev": "node . | pino-pretty -i pid,hostname -t yyyy-mm-dd HH:MM:ss"
	},
	"keywords": [],
	"author": "",
	"license": "ISC"
}

In the example above, further arguments are passed to pino-pretty to modify the generated output. -i pid,hostname hides these two elements from logged lines and -t yyyy-mm-dd HH:MM:ss formats the timestamp into an easy to use format. Try out what works for you! The official pino-pretty documentationopen in new window explains all possible arguments.

To start your bot with prettified input you run the dev script via your package manager of choice:

npm run dev

yarn run dev

pnpm run dev

Pino is very flexible, supports custom log levels, worker threads and many more features. Please check out the official documentationopen in new window if you want to up your pino game! Below we show an alternative for a production setup. Using this code, you will be logging the raw json objects into a file, instead of printing to your console:

const pino = require('pino');
const transport = pino.transport({
	target: 'pino/file',
	options: { destination: './log.json' },
});
const logger = pino(transport);
module.exports = logger;

# i18next

i18next is an internationalization-framework for JavaScript. It is beneficial to translate your bot's user-facing messages into various languages based on the server it is used in.

Covering an entire use case example for internationalization would be out of this guide's scope and requires some more explanation as to how the system operates. Please refer to the official documentation linked above for an in-depth usage guide.