How to Use the New ServeMux in Go 1.22+ (Method Matching, Wildcards)

Use http.NewServeMux() to create a router that supports method-specific handlers and wildcard patterns via HandleFunc or Handle.

package main

import (
	"net/http"
)

func main() {
	mux := http.NewServeMux()

	// Method matching: GET /api/items
	mux.HandleFunc("GET /api/items", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("GET items"))
	})

	// Wildcard: /static/* matches /static/css/style.css
	mux.Handle("/static/", http.FileServer(http.Dir("./static")))

	http.ListenAndServe(":8080", mux)
}

In Go 1.22+, ServeMux automatically matches HTTP methods when using HandleFunc with a method-prefixed pattern (e.g., GET /path). Wildcards like /static/* are supported by passing a handler to Handle for the prefix.

ServeMux is Go's built-in HTTP router that directs requests to the right function based on the URL and method. It lets you handle different actions (like GET vs POST) on the same path and serve files from folders using wildcards. Think of it as a traffic cop that sends web requests to the correct destination without extra setup.