Next.js

Here are some Next.js specific types you can use.

Static Generation and Server-side Rendering

For getStaticProps, getStaticPaths, and getServerSideProps, you can use the GetStaticProps, GetStaticPaths, and GetServerSideProps types respectively:

import { GetStaticProps, GetStaticPaths, GetServerSideProps } from 'next'

export const getStaticProps: GetStaticProps = async context => {
  // ...
}

export const getStaticPaths: GetStaticPaths = async () => {
  // ...
}

export const getServerSideProps: GetServerSideProps = async context => {
  // ...
}

API Routes

The following is an example of how to use the built-in types for API routes:

import { NextApiRequest, NextApiResponse } from 'next'

export default (req: NextApiRequest, res: NextApiResponse) => {
  // ...
}

Custom App

You can convert pages/_app.js into pages/_app.tsx and use the built-in type AppProps, like so:

import { AppProps } from 'next/app'

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

export default App

Converting Your App

To convert the blog app we created in the basics lessons into TypeScript, update the following files:

• components/date.js: Update to date.tsx using this code
• components/layout.js: Update to layout.tsx using this code
• lib/posts.js: Update to posts.ts using this code
• pages/posts/[id].js: Update to [id].tsx using this code
• pages/index.js: Update to index.tsx using this code
• pages/_app.js: Update to _app.tsx using this code
• pages/api/hello.js: Update to hello.ts using this code

Also, since remark-html doesn’t have type definitions within the package or in DefinitelyTyped, create a top-level global.d.ts file to add a type declaration.

declare module 'remark-html' {
  const html: any
  export default html
}

That’s it! Your app is now powered by TypeScript.

To learn more about using Next.js in TypeScript, take a look at our documentation.