Avneesh Agarwal

Posted on Aug 23, 2021 • Edited on Feb 16, 2023 • Originally published at blog.avneesh.tech

Add Typescript, TailwindCSS, and ESlint to your Next.js app

#typescript #javascript #tailwindcss #nextjs

Setting up the app

Creating a Next.js app

npx create-next-app next-tailwind-ts-demo

Starting the app

yarn dev # yarn
npm run dev # npm

Open localhost:3000 in your browser and you will be able to see a starter template of a Next.js app.

Cleanup

Delete everything under the Head tag until the footer like this

import Head from "next/head";

export default function Home() {
  return (
    <div>
      <Head>
        <title>Create Next App</title>
        <meta name="description" content="Generated by create next app" />
        <link rel="icon" href="/favicon.ico" />
      </Head>
    </div>
  );
}

This will give you a clean canvas.

Typescript

What is Typescript?

TypeScript is a strongly typed programming language that builds on JavaScript giving you better tooling at any scale. It also provides better IntelliSense and fewer bugs in your app.

Add Typescript to the app

Install the dependencies needed-

 yarn add --dev typescript @types/react # yarn
 npm i -D typescript @types/react # npm

Create a tsconfig.json file in the root of the project

Now cut the terminal running the app and restart the terminal

yarn dev # yarn
npm run dev # npm

After you restart the server you should see this

If you have some experience with typescript then I would recommend you setting strict mode to true in tsconfig.json

 "strict": true,

To use Typescript you need to change the file extension from .js to .tsx.
I am going to change index.js to index.tsx and _app.js to _app.tsx.

In _app.tsx you will see an error similar to this that the props have a type of any

So add the type of AppProps and import it from "next/app"

import { AppProps } from "next/app";
import "../styles/globals.css";

function MyApp({ Component, pageProps }: AppProps) {
  return <Component {...pageProps} />;
}

export default MyApp;

Now you can use Typescript in your app 🎉.

TailwindCSS

What is TailwindCSS?

Tailwind is a CSS framework that helps you build websites very fast, without leaving your HTML.

I have been using Tailwind for quite a while now and would highly recommend you all trying it out.

Adding Tailwind to the app

Installing the dependencies -

yarn add -D tailwindcss@latest postcss@latest autoprefixer@latest # yarn
npm install -D tailwindcss@latest postcss@latest autoprefixer@latest # npm

Generating the config files -

npx tailwindcss init -p

This will generate tailwind.config.js and postcss.config.js

Adding the files to purge through
Replace the purge in tailwind.config.js with this

  purge: ["./pages/**/*.{js,ts,jsx,tsx}", "./components/**/*.{js,ts,jsx,tsx}"],

Change your globals.css

@tailwind base;
@tailwind components;
@tailwind utilities;

You need to restart the server

yarn dev # yarn
npm run dev # npm

Testing if it works-
In index.tsx I am going to create a centered hello world text with tailwind stylings

import Head from "next/head";

export default function Home() {
  return (
    <div className="w-screen h-screen flex justify-center items-center">
      <Head>
        <title>Create Next App</title>
        <meta name="description" content="Generated by create next app" />
        <link rel="icon" href="/favicon.ico" />
      </Head>
      <h1 className="text-5xl font-bold">Hello world</h1>
    </div>
  );
}

ESLint

What is ESLint ?

Linting tools like ESLint allow developers to discover problems with their JavaScript code without executing it. The primary reason ESLint was created was to allow developers to create their own linting rules. ESLint is designed to have all rules completely pluggable.

Let's add ESLint

Add this line inside scripts in package.json

 "lint": "next lint"

These are all the scripts in package.json

  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start",
     "lint": "next lint"
  },

Now run

yarn lint # yarn
npm run lint # npm

After running this you will see a dropdown asking "How would you like to configure ESLint?". Just let it be the default one and then it will take some time to install the dependencies.

Now we have ESLint ready in our app 🥳.

Checking for the linter

If you are using bad practices in your code then it would highlight it with a yellow underline. For example, if I use the normal image instead of Next Image.