Next.js Rolls Out Version 9

Next.js 9 brings zero-config TypeScript support and automatic static optimization.

Recently, Next.js team rolled out the latest Next.js version 9. Next.js 9 features built in zero-config TypeScript support, automatic static optimization, API routes and improved developer experience. The new version also brings file system-based dynamic routing.
The team said that all of the new features are backwards compatible.
To update to the latest version you can make use of command: $ npm i next@latest react@latest react-dom@latest
The team said that they have integrated TypeScript support into the Next.js core.
Automated Setup: For getting started with TypeScript in Next.js just rename any file, page or component, from ‘.js’ to ‘.tsx’ and run ‘next dev’. Next.js will detect automatically which TypeScript is being used in your project and the Next.js CLI will guide you through installing all the required types for React and Node.js. It will also create a default ‘tsconfig.json’ with sensible defaults, if not already present.
Integrated Type-Checking: During in development Next.js will show you type errors when you save a file. Here, type-checking happens in the background and you get to interact with your updated application in the browser instantly. Type errors will propagate to the browser as they become available. It will also automatically fail the production build if type errors are present to help you prevent shipping broken code to production.
 Next.js 9
Source: nextjs 
The new version enables you to express complex application routing requirements via the file system without requiring a custom server and develop ultra-fast websites that leverage Server-Side Rendering and Static Prerendering now by default without compromising on features. You can now quickly build back-end application endpoints, leveraging hot-reloading and a unified build-pipeline.
To learn more you can visit the official announcement here.