fix cors

main.go

@@ -34,6 +34,12 @@ func main() {
 
 	router := router.New()
 
+	router.Handle("OPTIONS /", func(w http.ResponseWriter, r *http.Request) error {
+		w.WriteHeader(200)
+		fmt.Fprintf(w, "ok")
+		return nil
+	})
+
 	router.Handle("POST /auth/register", func(w http.ResponseWriter, r *http.Request) error {
 		var body struct {
 			Email    string `json:"email"`

router/router.go

@@ -32,6 +32,11 @@ func (router *router) SendJSON(w http.ResponseWriter, data any) error {
 
 func (router *router) Handle(pattern string, handler func(w http.ResponseWriter, r *http.Request) error) {
 	router.mux.HandleFunc(pattern, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Credentials", "true")
+		w.Header().Set("Access-Control-Allow-Origin", "http://localhost:3000")
+		w.Header().Set("Access-Control-Allow-Methods", "GET,POST,PATCH,DELETE,OPTIONS")
+		w.Header().Set("Access-Control-Allow-Headers", "Content-Type,Content-Length")
+
 		if err := handler(w, r); err != nil {
 			router.SendJSON(w, struct {
 				Error string `json:"error"`