Sample code for my article

cors-redirection-demo.go

package main

import (
	"fmt"
	"net/http"
)

func handleNoCors(w http.ResponseWriter, req *http.Request) {
	fmt.Println("Request received. Referer:", req.Header.Get("Referer"))
	w.Write([]byte("Hello world!"))
}

func handleCors(w http.ResponseWriter, req *http.Request) {
	fmt.Println("[/cors] Request received. Referer:", req.Header.Get("Referer"))
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Access-Control-Allow-Origin", "http://www.example.com")
	w.Write([]byte("{\"msg\":\"success\"}"))
}

func handleCorsRedirection(w http.ResponseWriter, req *http.Request) {
	fmt.Println("[/cors-redirect] Request received. Referer:", req.Header.Get("Referer"))
	w.Header().Set("Access-Control-Allow-Origin", "http://www.example.com")
	w.Header().Set("Location", "/cors")
	w.WriteHeader(http.StatusFound)
}

func handleNoCorsRedirection(w http.ResponseWriter, req *http.Request) {
	fmt.Println("[/no-cors-redirect] Request received. Referer:", req.Header.Get("Referer"))
	w.Header().Set("Location", "/cors")
	w.WriteHeader(http.StatusFound)
}

func main() {
	http.HandleFunc("/cors", handleCors)
	http.HandleFunc("/nocors", handleNoCors)
	http.HandleFunc("/cors-redirect", handleCorsRedirection)
	http.HandleFunc("/no-cors-redirect", handleNoCorsRedirection)

	http.ListenAndServe(":3000", nil)
}