Learning TypeScript with Next.js

Understand the Basics of TypeScript

This is demo content.

• Start with TypeScript basics: learn about types, interfaces, unions, and generics.
• Resources:
  • TypeScript Handbook
  • Tutorials on YouTube or platforms like FreeCodeCamp.

Leverage Next.js TypeScript Documentation

• Refer to the Next.js TypeScript Documentation.
• Set up TypeScript in your project:
  • Create a tsconfig.json file.
  • Let Next.js auto-generate types for pages, APIs, and components.

Use TypeScript Utility Types

Next.js has built-in types you can use:

• For pages:

import type { NextPage } from 'next';
 
const HomePage: NextPage = () => {
  return <div>Welcome to Next.js!</div>;
};
 
export default HomePage;

• For API routes:

import type { NextApiRequest, NextApiResponse } from "next";
 
export default function handler(req: NextApiRequest, res: NextApiResponse) {
  res.status(200).json({ message: "Hello, World!" });
}

Understand Common Patterns

Learn where you need types in Next.js:

• Props for Components:

type MyComponentProps = {
  title: string;
  onClick: () => void;
};
 
const MyComponent: React.FC<MyComponentProps> = ({ title, onClick }) => {
  return <button onClick={onClick}>{title}</button>;
};

• Static Props/Paths:

import { GetStaticProps } from 'next';
 
export const getStaticProps: GetStaticProps = async () => {
  return { props: { message: 'Hello!' } };
};
 
type Props = { message: string };
 
const Page: React.FC<Props> = ({ message }) => <div>{message}</div>;
 
export default Page;

Explore Next.js with TypeScript Examples

• Clone and explore projects from the Next.js TypeScript examples.

Install Type Definitions

• Install type definitions for libraries:

npm install --save-dev @types/react @types/node

• Next.js provides built-in TypeScript support for next and next-auth.

Use VS Code with TypeScript Plugins

• Install the TypeScript and ESLint plugins for better error highlighting and auto-completion.
• Set up eslint-config-next for linting with TypeScript:

npm install eslint-config-next

Refer to Common Errors

Learn to debug common warnings:

• Missing Types: Look for type definitions or create your own using interface or type.
• "Type 'X' is not assignable to type 'Y'": Identify the mismatch and adjust the expected or assigned type.

Practice

Build small projects like a to-do app or a blog to practice:

• Typing data from APIs.
• Using TypeScript with React hooks (e.g., useState, useEffect).
• Working with custom types in components.

Ask for Help

If you're stuck:

• Share the code snippet and error messages (e.g., GitHub Discussions, Stack Overflow).
• Reach out to TypeScript or Next.js communities.

By consistently practicing and referring to the right resources, you'll gain confidence and quickly pick up how to assign the correct types in Next.js projects.