Tari Ibaba, Author at Coding Beauty

How to get the difference between two arrays in JavaScript

By Tari Ibaba / Last updated on November 6, 2023

Get asymmetric difference between two arrays

To get the difference between two arrays in JavaScript, use the filter() and include() array methods, like this:

function getDifference(arrA, arrB) {
  return arrA.filter((element) => !arrB.includes(element));
}

const arr1 = [1, 2, 3, 4];
const arr2 = [2, 4];

console.log(getDifference(arr1, arr2)); // [1, 3]

Array filter() runs a callback on every element of an array and returns an array of elements that the callback returns true for:

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const evenNumbers = numbers.filter(
  (number) => number % 2 === 0
);

console.log(evenNumbers); // [2, 4, 6, 8, 10]

The Array includes() method returns true if the Array contains a particular element and returns false if it doesn’t:

const arr = ['a', 'b', 'c'];

console.log(arr.includes('b')); // true

If we wanted to find the difference between two Sets, we’d have used Set has() in place of Array includes():

function getDifference(setA, setB) {
  return new Set(
    [...setA].filter(element => !setB.has(element))
  );
}

const set1 = new Set([1, 2, 3, 4]);
const set2 = new Set([2, 4]);

console.log(getDifference(set1, set2)); // {1, 3}

Get symmetric difference between two arrays

The method above only gives the methods in the second array that aren’t in the first:

function getDifference(arrA, arrB) {
  return arrA.filter((element) => !arrB.includes(element));
}

const arr1 = [1, 3];
const arr2 = [1, 3, 5, 7];

console.log(getDifference(arr1, arr2)); // []

You want this sometimes, especially if arr2 is meant to be arr1‘s subset.

But other times you may want to find the symmetric difference between the arrays; regardless of which one comes first.

To do that, we simply merge the results of two getDifference() calls, each with the order of the arrays reversed:

function getDifference(arrA, arrB) {
  return arrA.filter((element) => !arrB.includes(element));
}

function getSymmetricDifference(arrA, arrB) {
  return [
    ...getDifference(arrA, arrB),
    ...getDifference(arrB, arrA),
  ];
}

const arr1 = [1, 3];
const arr2 = [1, 3, 5, 7];

console.log(getSymmetricDifference(arr1, arr2)); // [5, 7]
console.log(getSymmetricDifference(arr2, arr1)); // [5, 7]

How to get the difference between two sets in JavaScript

By Tari Ibaba / Last updated on November 6, 2023

Get asymmetric difference between two sets

To get the difference between two sets in JavaScript, use the Array filter() and Set has() methods like this:

function getDifference(setA, setB) {
  return new Set(
    [...setA].filter(element => !setB.has(element))
  );
}

const set1 = new Set([1, 2, 3, 4]);
const set2 = new Set([2, 4]);

console.log(getDifference(set1, set2)); // {1, 3}

The Set has() method returns true if the Set contains a particular element and returns false if it doesn’t.

const arr = ['a', 'b', 'c'];

const set = new Set(arr);

console.log(set.has('a')); // true

Array filter() runs a callback on every element of an array and returns an array of elements that the callback returns true for.

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const evenNumbers = numbers.filter(
  (number) => number % 2 === 0
);

console.log(evenNumbers); // [2, 4, 6, 8, 10]

The spread syntax (...) converts the set to an array for filter() to work.

The Set() constructor converts the result of filter() back to an Set.

Get symmetric difference between two sets

The method above only gives the elements in the second set that aren’t in the first.

function getDifference(setA, setB) {
  return new Set(
    [...setA].filter((element) => !setB.has(element))
  );
}

const set1 = new Set([2, 4]);
const set2 = new Set([1, 2, 3, 4]);

// Every item in set1 is also in set2, but the sets are different
console.log(getDifference(set1, set2)); // {}

Sometimes you want this, especially if set2 is supposed to be a set1‘s subset.

But other times you may want to find the symmetric difference between the sets, regardless of which one comes first.

To do that, we simply merge the results of two getDifference() calls, each with the order of the Sets reversed.

function getDifference(setA, setB) {
  return new Set(
    [...setA].filter((element) => !setB.has(element))
  );
}

function getSymmetricDifference(setA, setB) {
  return new Set([
    ...getDifference(setA, setB),
    ...getDifference(setB, setA),
  ]);
}

const set1 = new Set([2, 4]);
const set2 = new Set([1, 2, 3, 4]);

console.log(getSymmetricDifference(set1, set2)); // {1, 3}
console.log(getSymmetricDifference(set2, set1)); // {1, 3}

How to easily detect when the mouse leaves the browser window in JavaScript

By Tari Ibaba / Last updated on November 2, 2023

Detecting when the mouse leaves the browser window helps to track user engagement and display custom messages or popups.

Let’s learn how to do it with JavaScript.

Detect browser window mouse exit

To detect when the mouse leaves the browser window, use the mouseleave event listener:

<!DOCTYPE html>
<html>
  <head>
    <title>Coding Beauty Tutorial</title>
    <link rel="icon" href="favicon.ico" />
  </head>
  <body>
    <div id="notifier"></div>
    <button class="btn-1">Be amazing</button>
    <script src="index.js" />
  </body>
</html>

document.addEventListener('mouseleave', () => {
  document.querySelector('#notifier').textContent =
    "Don't leave me!";
});

The mouseleave event fires on an Element when the mouse exits its bounds.

You can also use document.body to listen for when the user exits the window, but the body needs to be as big as the viewport for this to work:

document.addEventListener('mouseleave', () => {
  document.querySelector('#notifier').textContent =
    "Don't leave me!";
});

<!DOCTYPE html>
<html>
  <head>
    <title>Coding Beauty Tutorial</title>
    <link rel="icon" href="favicon.ico" />
    <style>
      /* Makes body as big as viewport */
      html,
      body {
        margin: 0;
        height: 100%;
        width: 100%;
      }
    </style>
  </head>
  <body>
    <h2>Welcome fellow developer</h2>
    <div id="notifier"></div>
    <script src="index.js"></script>
  </body>
</html>

Using document.body over document could be better for compatibility with later Firefox versions.

Detect when user about to exit webpage

This helps to display an exit-intent popup, usually shown when the user is about to close the webpage or go to another.

Since tabs are usually at the top of the browser, we’d detect when the mouse leaves the browser window, but only from the top:

document.addEventListener('mouseleave', (event) => {
  if (event.clientY <= 0) {
    document.querySelector('#notifier').textContent =
      'Have a good day!';
  }
});

clientY will be 0 at the very top of the viewport, so any higher and our if block’s code runs.

<!DOCTYPE html>
<html>
  <head>
    <title>Coding Beauty Tutorial</title>
    <link rel="icon" href="favicon.ico" />
  </head>
  <body>
    <h2 id="notifier"></h2>
    <div>
      Welcome to Coding Beauty, a site for all things
      coding.
    </div>
    <script src="index.js" />
  </body>
</html>

Create React App alternative: 5 times leaner, 0 vulnerabilities

By Tari Ibaba / Last updated on November 25, 2023

Create React App is gone.

Yes, it’s no longer the recommended tool for starting React apps. Some of us were surprised, but many of us knew it was a long time coming.

There are much faster and leaner alternatives available today.

Why shouldn’t you use Create React App anymore?

Create React App was great.

Setting up React apps become as easy as ever without any need to bother with tedious Webpack and Babel configs. But despite the convenience, it had notable issues we just couldn’t ignore:

1. Bulky and slow

Create React App is a bloated tool.

It installs an unbelievable number of packages and takes forever to finish. If you’re a long-time CRA user like me, you’ve probably gotten used to this process, but it’s far from normal.

Once you enter the command to start a new project, you will quickly realize the insane number of packages CRA needs to set up.

Look at how large the node_modules folder is for CRA compared to Vite, a superior alternative. And both folders were just newly set up.

Many packages mean longer install times, even if you’re using PNPM or Yarn 2.

2. Insecure and outdated packages

Bundling so many packages makes it harder to keep track of them all, and many become abandoned and insecure later.

Things improved but any insecure package is something to worry about, and there are still quite a few.

Create React App has 8 high security vulnerabilities. — 8 high security vulnerabilities! And that’s even better than what it used to be.

In my GitHub repos using CRA, I get several Dependabot alerts at every turn – even from one of my first GitHub projects.

And they’re almost always about security flaws in packages CRA installed.

Security weaknesses found in npm packages installed during Create React App setup.

3. Limited customization options

Create React App is a black box.

To add new libraries and customize it you usually have to depend on libraries like Craco – heck, before CRA version 5, Craco was pretty much our only way to get Tailwind CSS support.

I remember my earlier days of creating various Electron + React desktop apps, where I had to install react-app-rewired just to set the target to 'electron-renderer' to access Node modules in the React part of the app.

For total control, you can always do npm eject, but of course, then you become responsible for all the dependencies installed by CRA, which has trade-offs that may not be worth it for you.

What to use instead of Create React App

Old habits die hard, sure.

If you’ve been hesitating to switch to a superior tool, hopefully, the React team dumping CRA should finally do it for you. There are far more modern and better-maintained alternatives out there; let’s check out some of the most popular ones:

Vite

It’s a fast way to build modern web projects, designed for efficiency and smoother development.

The VueJS team is responsible for developing and maintaining Vite, so you can trust it’s a reliable tool.

“Extremely fast” Hot Module Replacement (HMR).
Out-of-the-box support for TypeScript.
A lightning-fast SWC compiler.

HMR means that code changes show instantly in the browser, avoiding full-page refreshes and saving valuable time.

It provides just about everything CRA does – but better and without the bloat. And it’s constantly being updated.

Here you don’t worry about outdated dependencies or vulnerable packages:

The Vite project has zero vulnerabilities. — Zero vulnerabilities.

Parcel

It’s a zero-config bundler with no setup required, yet it’s still more flexible than Create React App.

Parcel supports all the latest web technologies, including React, Vue, and TypeScript, and it can bundle any type of asset, from images and CSS to HTML and JavaScript.

Plus, it has excellent performance, thanks to its use of worker threads, which allows it to parallelize tasks and speed up builds.

Parcel also has HMR support and is updated often with the latest features and optimizations like Vite. You can trust the team to keep up with the latest web technologies and best practices.

And what’s the result: your projects are built with the best tools available.

Custom Webpack configuration

Webpack is still king if you know what you’re doing.

The level of control of flexibility it gives you is unmatched as there are a massive number of options you can set, far more than just path and filename.

Another benefit to note: Webpack can generate a development build without a local server, unlike Parcel and others.

This particular feature saved me when I was debugging React in a VSCode extension. Loading data from localhost didn’t work properly for a Webview; I had to build to a local file and read the contents.

With source maps enabled and dev mode turned on, I could easily see the exact line where the error occurred in the TS code. Unlike with Parcel, where all I got was a minified build.

Of course, setting up a Webpack config can be complex and more involved – which is why CRA came around in the first place. You must configure various options to get everything working perfectly.

But once you’re set-up, you’ll have a heavily personalized build process for your project. It’s a trade-off that may or may not be worth it for you.

Frameworks to replace Create React App

Need React’s state and UI capabilities without extras? The tools we’ve seen are great.

Want high-performance apps with advanced features like SSR? Then consider frameworks with built-in routing, data fetching, etc.

Frameworks like:

Next.js

Many of us already know Next.js with advanced features like server-side rendering and static website generation.

Server-side rendering renders pages on the server and sends them to the client, greatly boosting performance, user experience, and SEO scores.

With intuitive file-based routing and built-in image optimization, Next.js is a smart option for building high-flying web apps with speed.

Remix

Another SSR-enable framework with powerful data features like:

Intelligent network error handling
Parallel fetching of CSS, JavaScript, and other assets to save time
Automatically ensuring the UI data is in sync with the server data after a user action.

One stand-out Remix feature is nested routes, which makes it possible to associate a specific section of a page with a particular route segment so that only that section updates when the route segment changes. This accelerates page transitions as no time is wasted re-rendering the entire page.

Gatsby

Gatsby is another awesome one – for scalable & fast-loading static sites.

There are a variety of starter kits and plugins to easily extend your site’s functionality and build a blog, e-commerce site, or portfolio site in no time at all.

With Gatsby, it’s effortless to power up your app with data from a CMS, especially with the GraphQL data layer for rapid integration with various APIs and services.

Final thoughts

CRA was a popular tool.

But it had its issues. It was bulky, outdated, and had limited customization.

Adaptation is crucial in the dynamic landscape of web development. By embracing modern tools, such as Vite, and Parcel, and in-depth frameworks like Next.js, Remix, and Gatsby, we can build faster and more efficient React apps.

How to easily fix the “Cannot read property ‘classList’ of null” error in JavaScript

By Tari Ibaba / Last updated on October 30, 2023

The “Cannot read property ‘classList’ of null” error happens in JavaScript when you try to access the classList property on an element that isn’t in the HTML DOM.

Let’s look at various ways to quickly fix this error.

Fix: Ensure correct selector

To fix the “Cannot read property ‘classList’ of null” error in JavaScript, ensure the correct selector accesses an existing HTML element.

<div>Welcome to Coding Beauty</div>
<button class="btn-1">Be amazing</button>

Check for any mistakes in the selector symbols in the script. Check for any mistakes in the ID or class name in the HTML tag. Maybe you forgot to set that id or class attribute at all?

// forgot the '.' symbol used for class selectors 
const button = document.querySelector('btn-1');

console.log(button); // 👉️ undefined

// ❌ Uncaught TypeError: Cannot read properties of undefined (reading 'classList')
button.classList.add('active');

Fix: Ensure DOM load before `.classList` access

The “Cannot read property ‘classList’ of undefined” error also occurs when you try to access .classList on an element that the browser hasn’t added to the DOM yet.

Maybe because your <script> is in the <head> tag and executes before the element’s parsing:

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Coding Beauty Tutorial</title>
    <!-- ❌ Script is run before button is declared -->
    <script src="index.js"></script>
  </head>
  <body>
    <div id="element">
      console.log('Easy answers to your coding questions and more...');
    </div>
  </body>
</html>

The script tag is placed in the <head> tag above where the div is declared, so index.js can’t access the div.

const element = document.querySelector('.element');
console.log(element); // 👉️ undefined

// ❌ Uncaught TypeError: Cannot read properties of undefined (reading 'classList')
element.classList.add('highlight');

Solution: Move script to bottom

To fix the error in this case, move the script tag to the bottom of the body, after all the HTML elements have been declared.

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Coding Beauty Tutorial</title>
    
  </head>
  <body>
    <div id="element">
      console.log('Easy answers to your coding questions and more...');
    </div>
    
    <!-- ❌ Script is run after element is added to the DOM -->
    <script src="index.js"></script>
  </body>
</html>

Now index.js will have access to the div and all the other HTML elements, because the browser would have rendered them by the time the script runs:

const element = document.querySelector('.element');
console.log(element); // 👉️ undefined

// ✅ Works as expected
element.classList.add('highlight');

Solution: Access `.classList` in `DOMContentLoaded` event listener

Another way to fix the “cannot read property ‘addEventListener’ of null” error is to add a DOMContentLoaded event listener to the document and access the element in this listener.

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Coding Beauty Tutorial</title>
    <!-- Script placed above accessed element -->
    <script src="index.js"></script>
  </head>
  <body>
    <div id="element">
      console.log('Coding is more than a means to an end...');
    </div>
  </body>
</html>

The DOMContentLoaded event fires when the browser fully parses the HTML, whether or not external resources like images and stylesheets have loaded.

So regardless of where we place the script, the code in the listener only runs after every element is active in the DOM.

const element = document.querySelector('.element');
console.log(element); // 👉️ undefined

// ✅ Works as expected
element.classList.add('highlight');

How to easily add a favicon to a Next.js app

By Tari Ibaba / Last updated on October 30, 2023

Adding a favicon to a website enhances usability and branding. It helps identify the website in browser tabs and bookmarks, improving user recognition and trust.

Let’s learn how to quickly add a favicon image to a Next.js app

Add favicon automatically in Next.js 13 App Router

To add a favicon in Next.js 13 App Router, add a favicon.ico file to the app/ directory. Next.js will automatically detect favicon.ico and display it on the page.

Here we’ve added the favicon.ico to our VS Code Next.js project.

favicon.ico is the app directory in Visual Studio Code.

And this is all we need to do – here’s layout.tsx:

import { Metadata } from 'next';
import './globals.css';

export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <html lang="en">
      <body>{children}</body>
    </html>
  );
}

And we’ll instantly see the image next to the page title in the browser tab:

The favicon shows up next to the page title in the browser-tab

Apart from favicon and .ico, Next.js also auto-discovers the following file name and extension combinations in the app/ directory

icon with .ico, .jpg, .jpeg, .png, or.svg extension.
app-icon with .jpg, .jpeg, .png extension.

You can rename PNGs to .ico files and they will still work.

Add favicon automatically in Next.js Pages Router

To add a favicon automatically in the Next.js pages directory, place a favicon.ico file in your public/ directory, and your browser will automatically detect the file for the site icon.

favicon.ico is the public directory in Visual Studio Code.

If your image file isn’t a .ico, you’ll need to either rename it to favicon.ico, or manually specify the filename.

Set Next.js favicon statically in Next.js 13 App Router

To add a favicon to a Next.js 13 app, you can also export a Metadata object with an icons property in your layout.tsx file:

import { Metadata } from 'next';
import './globals.css';

export const metadata: Metadata = {
  icons: {
    icon: '/icon.png',
  },
};

export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <html lang="en">
      <body>{children}</body>
    </html>
  );
}

The image file should be in your public directory.

Set Next.js favicon with HTML in Pages Router

To add a site icon in the Next.js pages or app directory, use the HTML <link> tag in your _document.tsx or _document.js file, just like in vanilla HTML:

import { Html, Head, Main, NextScript } from 'next/document';

export default function Document() {
  return (
    <Html lang="en">
      <Head>
        <link rel="icon" href="/favicon.png" />
      </Head>
      <body>
        <Main />
        <NextScript />
      </body>
    </Html>
  );
}

The favicon should be in your public directory.

Add favicon with HTML in Next.js 13 App Router

You can also use the HTML <link> tag to add a favicon in a project using the Next.js app directory, in your layout.tsx file:

import './globals.css';

export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <html lang="en">
      <head>
        <link rel="icon" href="/app-icon.jpg" />
      </head>
      <body>{children}</body>
    </html>
  );
}

The favicon should be in your public directory.

How to add or toggle a class on the body element in JavaScript

By Tari Ibaba / Last updated on October 26, 2023

Adding a class to the <body> tag can be useful for applying global styles or targeting specific elements within the body for styling or functionality.

This article will teach us how to easily add or toggle a class on the HTML body element using JavaScript.

Add class to body tag in `<head>` tag

To add a class to the body element in the <head> tag using JavaScript, use the DOMContentLoaded event and the document.body.classList.add() method.

For example:

<!DOCTYPE html>
<html>
  <head>
    <title>Coding Beauty Tutorial</title>
    <script>
      document.addEventListener('DOMContentLoaded', () => {
        document.body.classList.add('beauty', 'magic');
      });
    </script>
  </head>
  <body class="dev coding">
    <div>This is a div element.</div>
    <script src="index"></script>
  </body>
</html>

The DOMContentLoaded event runs when the HTML is completely parse and the DOM has loaded.

The <script> loads and the JavaScript runs before the browser renders the HTML, so without DOMContentLoaded, document.body will be null in the <script>, causing the “Cannot read property ‘classList’ of undefined” JavaScript error.

The "Cannot read property 'classList' of undefined" error happening in JavaScript.

Add class to body tag on click

If you’d like to add a class to the body tag when the user clicks an element, set a click listener on element and call document.body.classList.add() in this listener.

For example:

<!DOCTYPE html>
<html>
  <head>
    <title>Coding Beauty Tutorial</title>
  </head>
  <body class="dev coding">
    <div>So you can code</div>
    <button class="amazify">Be amazing</button>
  </body>
</html>

const button = document.getElementById('amazify');

button.addEventListener('click', () => {
  document.body.classList.add('amazify');
});

Toggle class on body element

Toggling a class on the body element in JavaScript simplifies code implementation by handling the addition and removal of the class in a single line of code.

And this single line of code is a call to the body’s classList.toggle() method:

document.body.classList.toggle('incredible');

As you would expect, the class is removed from the body when it’s already there and added when it isn’t.

Next.js: How to set page title and meta description

By Tari Ibaba / Last updated on October 21, 2023

Setting the page title and meta description helps improve search engine visibility, increase click-through rates, and provide concise summaries of webpage content.

In this article, we’re going to learn how we easily set the page title and meta description in a Next.js project.

Set static page title and meta description in Next.js App Router

To set page title and meta description statically in Next.js 13’s app directory, create a Metadata object in a page.tsx file and export it:

import React from 'react';
import { Metadata } from 'next';

export const metadata: Metadata = {
  title: 'Coding Beauty',
  description:
    'codingbeautydev.com: Coding - the art, the science, and the passion.',
};

export default function Page() {
  return (
    <main>
      <h1>Welcome to Coding Beauty</h1>
    </main>
  );
}

The tab will have this title, and the page will have a meta tag containing this description:

A Next.js page with a title and meta description.

We can also do this in a layout.tsx to make every page using this layout have this title and meta description by default – if the page doesn’t have its own.

import { Metadata } from 'next';
import '@/styles/globals.css';

export const metadata: Metadata = {
  title: 'Coding Beauty',
  description: 'The official Coding Beauty home page.',
  icons: {
    icon: '/favicon.png',
  },
};

export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <html lang="en">
      <body>{children}</body>
    </html>
  );
}

Set title and meta description dynamically in Next.js App Router

You can use the generateMetadata() function to set the page title and meta description using dynamic information we don’t know beforehand, like data from an API.

export function generateMetadata({ params }: Props): Promise<Metadata> {
  // fetch data with `params`

  // return a `Metadata` object
  return {
    title: post.name,
    description: post.description,
  }
}

Let’s look at a full example, where we fetch API data for a post in our hypothetical social media app, and we use generateMetadata() to set the page title and meta description for the page based on what we get from the endpoint URL.

import { Metadata } from 'next';

type Props = {
  params: { id: string };
};

export async function generateMetadata({
  params,
}: Props): Promise<Metadata> {
  const id = params.id;
  const url = `https://api.mysocialapp.com/posts/${id}`;

  const post = await fetch(url).then((res) => res.json());

  return {
    title: post.title,
    description: post.description,
  };
}

export default async function Page({ params }: Props) {
  const { id } = params;
  const url = `https://api.mysocialapp.com/posts/${id}`;

  // fetch again!
  // But don't worry, Next.js caches the `fetch()` calls
  const post = await fetch(url).then((res) => res.json());

  return (
    <>
      <h1>{post.title}</h1>
      <div>{post.content}</div>
    </>
  );
}

We fetch data from the same endpoint twice, one for the title and meta description, and another to display the title and other information to the actual users on the page.

Next.js caches the results of the fetch in generateMetadata() for use in Page to prevent multiple requests and avoid performance hits.

If you export a Metadata object and also have generateMetadata() function, Next.js will use generateMetadata()‘s return value.

Set page title and meta description in Next.js Pages Router (<= 12)

To set the page title and meta description in the Next.js pages directory, create a Head component, and place meta and title tags in it, like you would in vanilla HTML:

import Head from 'next/head';

export default function Home() {
  return (
    <>
      <Head>
        <title>Coding Beauty</title>
        <meta
          name="description"
          content="A brand all about coding passion and success"
        />
        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <link rel="icon" href="/favicon.png" />
      </Head>
      <main>
        <h1>Welcome to Coding Beauty</h1>
      </main>
    </>
  );
}

We can also set the page title and meta description in your _app.tsx or _app.jsx file to make each page without a title or description use this as a default.

import '@/styles/globals.css';
import type { AppProps } from 'next/app';
import Head from 'next/head';

export default function App({ Component, pageProps }: AppProps) {
  return (
    <>
      <Head>
        <title>Coding Beauty</title>
        <meta
          name="description"
          content="A page on the Coding Beauty website"
        />
      </Head>
      <Component {...pageProps} />
    </>
  );
}

Set page title and meta description dynamically in Next.js Pages Router (<= 12)

You can also set the page title and meta description in the pages directory based on some data not known ahead of time.

For instance, to set the meta information based on API data, you’ll fetch the data in getServerSideProps and display it in the title and meta tags that are in the Head tag.

import { GetServerSideProps } from 'next';
import Head from 'next/head';

export const getServerSideProps: GetServerSideProps = async (context) => {
  const { params } = context;
  const { id } = params!;

  const result = await fetch(`api.mystore.com/books/${id}`);
  const { title, description, details } = await result.json();

  return {
    props: {
      title,
      description,
      details,
    },
  };
};

export default function Home(props: any) {
  const { title, description, details } = props;

  return (
    <>
      <Head>
        {/* 👇 set page title and meta description dynamically */}
        <title>{title}</title>
        <meta name="description" content={description} />

        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <link rel="icon" href="/favicon.png" />
      </Head>
      <main>
        <h1>{title}</h1>
        <p>{details}</p>
      </main>
    </>
  );
}

Best laptops (for programming)

By Tari Ibaba / Last updated on October 10, 2023

Dell XPS 15 9000

View laptop

Screen size: 15.6”
Color: Black
Hard disk size: 512 GB
CPU model: Core i7
RAM: 16 GB
Resolution: 1920 x 1200
OS: Windows 11 Pro
Special features: InfinityEdge, Anti-glare screen
Graphics card: Arc A370M Graphics

How to create a type from type or object keys or values in TypeScript

By Tari Ibaba / Last updated on October 9, 2023

Create type from object keys in TypeScript

To create a type from an object’s keys in TypeScript, use the keyof typeof object. For example:

const brand = {
  name: 'Coding Beauty',
  domain: 'codingbeautydev.com',
  color: 'blue',
};

// 👇 type Keys = 'name' | 'domain' | 'color';
type BrandKeys = keyof typeof brand;

With this, you’ll have a type that only accepts strings matching the key name, and your code editor’s intellisense should indicate:

The new type only accepts values matching the object's keys. — The new type only accepts values matching the object’s keys.

Create type from another type’s keys in TypeScript

We use typeof because brand is an instance object, not a type. If it was a type, we would omit typeof:

type Brand = {
  name: string;
  domain: string;
  color: string;
};

// 👇 type Keys = 'name' | 'domain' | 'color';
type BrandKeys = keyof Brand;

As before, you’ll have a type that only contains strings matching the key name, and your code editor should detect this:

The new type only accepts values matching the first type's keys. — The new type only accepts values matching the first type’s keys.

Create type from object values in TypeScript

We can use typeof and type indexing to easily create a type from an object’s values in TypeScript:

const site = {
  url: 'codingbeautydev.com',
  color: 'blue',
  topic: 'coding',
} as const; // 👈 const assertion

// 👇 type Values = 'codingbeautydev.com' | 'color' | 'coding'
type Values = (typeof site)[keyof typeof site];

We this, we’ll have a type that only accepts strings matching the values of the object:

The new type only accepts values matching the object's values. — The new type only accepts values matching the object’s values.

Otherwise, there’ll be a TypeScript error

You can only values matching the object's values to the new type.

Create generic type from object values in TypeScript

The as const is called a const assertion in TypeScript. It tells the compiler to infer the most specific type possible from an expression. Without it, the inferred value type will be a primitive, like string or number or union of these primitives – string | number for example.

const site = {
  url: 'codingbeautydev.com',
  color: 'blue',
  topic: 'coding',
};

// 👇 type Values = 'string'
type Values = (typeof site)[keyof typeof site];

// 👇 No error - `Values` takes any string
const testObj: Values = 'random string';

Values is no different from the string type here, and VS Code confirms it:

The Values type is a string. — The `Values` type is a `string`.

If there are multiple primitive types, the resulting generic type will be a union of all those primitives:

const site = {
  url: 'codingbeautydev.com',
  age: 1000, // 👈 also `number` type now
  topic: 'coding',
};

// 👇 type Values = 'string' | number
type Values = (typeof site)[keyof typeof site];

// 👇 No error
const testObj: Values = 34124;

The Values type is a string | number type. — The `Values` type is a `string | number` type.

Create generic type from another type’s values in TypeScript

You can also create generic types from another type’s values in TypeScript, like this:

type Site = {
  url: 'codingbeautydev.com';
  age: number;
  topic: string;
};

// 👇 type Site = 'string' | 'number'
type Values = Site[keyof Site];

Tari Ibaba

Get asymmetric difference between two arrays

Get symmetric difference between two arrays

Get asymmetric difference between two sets

Get symmetric difference between two sets

Detect browser window mouse exit

Detect when user about to exit webpage

Why shouldn’t you use Create React App anymore?

1. Bulky and slow

2. Insecure and outdated packages

3. Limited customization options

What to use instead of Create React App

Custom Webpack configuration

Frameworks to replace Create React App

Final thoughts

Fix: Ensure correct selector

Fix: Ensure DOM load before .classList access

Solution: Move script to bottom

Solution: Access .classList in DOMContentLoaded event listener

In this article

Add favicon automatically in Next.js 13 App Router

Add favicon automatically in Next.js Pages Router

Set Next.js favicon statically in Next.js 13 App Router

Set Next.js favicon with HTML in Pages Router

Add favicon with HTML in Next.js 13 App Router

In this article

Add class to body tag in <head> tag

Add class to body tag on click

Toggle class on body element

In this article

Set static page title and meta description in Next.js App Router

Set title and meta description dynamically in Next.js App Router

Set page title and meta description in Next.js Pages Router (<= 12)

Set page title and meta description dynamically in Next.js Pages Router (<= 12)

Dell XPS 15 9000

In this article

Create type from object keys in TypeScript

Create type from another type’s keys in TypeScript

Create type from object values in TypeScript

Create generic type from object values in TypeScript

Create generic type from another type’s values in TypeScript

Fix: Ensure DOM load before `.classList` access

Solution: Access `.classList` in `DOMContentLoaded` event listener

Add class to body tag in `<head>` tag