How to Write Reusable Middleware for net/http

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2026-04-17T12:05:42+00:00
Write a function that accepts an `http.Handler` and returns a new `http.Handler` wrapping it to execute logic before or after the request.

How to Write Reusable Middleware for net/http

Write a function that accepts an http.Handler and returns a new http.Handler wrapping it to execute logic before or after the request.

package main

import (
	"fmt"
	"net/http"
)

func LoggingMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Println("Before:", r.URL.Path)
		next.ServeHTTP(w, r)
		fmt.Println("After:", r.URL.Path)
	})
}

// Usage:
// http.Handle("/", LoggingMiddleware(myHandler))

func main() {
	// Example usage
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("Hello, World!"))
	})

	http.ListenAndServe(":8080", LoggingMiddleware(http.DefaultServeMux))
}