Introduction to Next.js and Using Pages Router

If you are looking for a framework that makes developing web applications with React faster and easier, Next.js is one of the best options. Next.js provides outstanding capabilities for developers to create web applications that are efficient, scalable, and feature-rich. One of the most important features of this framework is the routing system called Pages Router, which allows you to quickly create new pages and manage them.

When using the Pages Router in Next.js, you can easily create your files and folders in the 'pages' directory, and Next.js automatically manages routing based on the structure of your directory. For example, if you create a file named 'about.js' in the 'pages' folder, the '/about' address will be automatically created for it. This approach makes your work very easy and fast.

Now, let's take a look at Next.js configuration options through the 'next.config.js' file, which is one of the essential parts of this framework. With this file, you can configure various settings, such as changes related to the server, folder structure, or different APIs.

Using 'instrumentationHook' can greatly aid your development and execution processes. This capability is suitable for tasks such as logging, monitoring, or executing specific codes under specific circumstances. To add this feature, it is necessary to make changes in the 'next.config.js' file.

Assume you want to execute a small JavaScript code at the beginning of all server requests. You can utilize 'instrumentationHook' to easily implement this feature.

Example Code and Line-by-Line Explanation

module.exports = {
  instrumentationHook: (phase, { defaultConfig }) => {
    console.log(`Phase: ${phase}`);
    return {
      ...defaultConfig,
      customConfig: true
    }
  }
}

module.exports: This line indicates that we are exporting configurations for Next.js.
instrumentationHook: This is a function that we want to execute during a specific phase.
phase: This variable specifies which phase (e.g., development or production) we are in.
defaultConfig: This represents the default configuration provided by Next.js.
console.log(`Phase: ${phase}`): This line logs the current phase in the console, which can be useful for monitoring and debugging.
return: At the end of this function, we are returning an updated configuration that can include additional settings.