Next.js Middleware & HOC

TODO: collapasable, copyable, download, etc

What is the best way to add instrumentation to every route in a NextJs app using the app router?Adding instrumentation to every route in a Next.js app can be crucial for monitoring performance, user behavior, and debugging. In Next.js, you can achieve this using a combination of middleware and higher-order components. Here’s a step-by-step approach:

1. Use Middleware (Next.js 12+)

Starting from Next.js 12, you can use middleware to run code before a request is completed. Middleware in Next.js can be applied globally, allowing you to add instrumentation to every route.

1. Create a Middleware File: In your Next.js project, create a file named _middleware.js or _middleware.ts in the pages directory. This will apply the middleware to all routes.

2. Add Instrumentation Logic: In the middleware, you can add any instrumentation logic, such as logging, performance tracking, etc. Here’s a simple example that logs the request path:

   import { NextResponse } from 'next/server';
   
   export function middleware(request) {
     console.log(`Request received for ${request.nextUrl.pathname}`);
     return NextResponse.next();
   }
   

3. Use External Services: If you're using services like Sentry, Datadog, or New Relic, you can integrate their SDKs within this middleware to capture more detailed telemetry data.

2. Use a Higher-Order Component (HOC)

For more granular control, especially if you need to wrap specific React components or pages, you can use a higher-order component.

1. Create an HOC: This HOC can wrap any component and add instrumentation logic, such as timing a page load or capturing user interactions.

   import React from 'react';
   
   const withInstrumentation = (WrappedComponent) => {
     return class extends React.Component {
       componentDidMount() {
         // Start timing or log
       }
   
       componentWillUnmount() {
         // End timing or log
       }
   
       render() {
         return <WrappedComponent {...this.props} />;
       }
     };
   };
   
   export default withInstrumentation;
   

2. Wrap Your Pages: Apply this HOC to your pages in pages directory.

   import withInstrumentation from '../path/to/withInstrumentation';
   
   function HomePage() {
     return <div>Welcome to the homepage!</div>;
   }
   
   export default withInstrumentation(HomePage);
   

3. Using Analytics and Monitoring Tools

Integrating analytics and monitoring tools like Google Analytics, Segment, or any APM tools can also be done within these patterns. For example, you can trigger events in middleware or within HOCs to log to these services.

4. Testing and Validation

Ensure to test the instrumentation thoroughly:

• Test in a development environment to ensure the logs and metrics are correctly captured.
• Validate that performance isn’t significantly impacted by the additional instrumentation.

By using these techniques, you can effectively add instrumentation to every route in your Next.js application, which can be immensely valuable for comprehensive monitoring and performance optimization.

Next.js Middleware & HOC created at Tue Jan 20 1970 20:29:20 GMT+0000 (Coordinated Universal Time)