9 Development vs. Production Mode in Next.js

Next.js offers two primary modes for developing and deploying web applications: Development mode and Production mode. These modes serve different functions in an application’s lifecycle and have distinct features. This chapter explains the differences between these modes and how to use them in Next.js.

9.1 Development Mode

The Development mode is intended for the development phase of an application. In this mode, Next.js provides features like Hot Reloading, meaning changes in the code are immediately visible in the browser without needing to reload the page. Additionally, detailed error messages and warnings are displayed to facilitate debugging.

9.1.1 Starting in Development Mode

To start a Next.js application in Development mode, use one of the following commands in your terminal:

For npm:

npm run dev

For yarn:

yarn dev

This launches the development server by default at http://localhost:3000.

9.2 Production Mode

The Production mode is intended for publishing and operating the application. In this mode, Next.js optimizes the application for the best performance. This includes minimizing JavaScript files, efficient loading of resources, and depending on the configuration, Server-Side Rendering or Static Site Generation.

9.2.1 Starting in Production Mode

To start a Next.js application in Production mode, you first need to create a production build and then execute the start command:

  1. Creating a Production Build:

    For npm:

    npm run build

    For yarn:

    yarn build

    This command creates an optimized build of your application.

  2. Starting the Application in Production Mode:

    For npm:

    npm start

    For yarn:

    yarn start

    This launches the application in Production mode on the default port http://localhost:3000, unless configured otherwise.

Choosing between Development and Production mode in Next.js depends on the current phase of your project development. While the Development mode is designed for active development with quick iterations and debugging support, the Production mode is geared towards the efficient operation of the finished application. Both modes are crucial for the effective development and deployment of web applications with Next.js.

9.3 Exercise: Switching Between Development and Production Modes in Next.js

9.3.1 Objective:

Familiarize yourself with the process of launching a Next.js application in both Development and Production modes. Understand the differences and the appropriate use cases for each mode.

9.3.2 Task:

  1. Create a basic Next.js application using create-next-app.
  2. Launch the application in Development mode and observe its features.
  3. Build and start the application in Production mode.
  4. Document the differences you observe between the two modes in terms of performance, console outputs, and any other noticeable aspects.

9.3.3 Requirements: