Couple small changes

Add extra HTTP verbs, Generate verb string representation,
disallow body for GET, HEAD, Use more pointers.

fetch/fetch/fetch.go

@@ -2,7 +2,10 @@
 
 package fetch
 
+//go:generate bash -c "GOROOT=$GOPATH/src/github.com/neelance/go/ GOOS=js GOARCH=wasm stringer -type Method"
+
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -13,28 +16,16 @@ import (
 
 type Method int
 
-func (m Method) String() string {
+// https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods
-	switch m {
-	case GET:
-		return "GET"
-	case POST:
-		return "POST"
-	case PUT:
-		return "PUT"
-	case DELETE:
-		return "DELETE"
-	case PATCH:
-		return "PATCH"
-	}
-
-	panic("unsupported method")
-}
-
 const (
 	GET Method = iota
+	HEAD
 	POST
 	PUT
 	DELETE
+	CONNECT
+	OPTIONS
+	TRACE
 	PATCH
 )
 
@@ -42,20 +33,26 @@ type Request struct {
 	Method  Method
 	URL     *url.URL
 	Headers http.Header
-	Body    []byte
+	Body    io.Reader
 }
 
 type Response struct {
-	URL        url.URL
+	URL        *url.URL
 	Headers    http.Header
-	Body       io.Reader
+	Body       io.ReadCloser
 	StatusCode int
 }
 
-func Fetch(req Request) (Response, error) {
+func Fetch(req *Request) (*Response, error) {
 	init := js.Global.Get("Object").New()
 	init.Set("method", req.Method.String())
-	init.Set("body", req.Body)
+	if req.Body != nil {
+		switch req.Method {
+		case GET, HEAD:
+			return nil, errors.New("cannot use body with GET or HEAD HTTP methods")
+		}
+		init.Set("body", req.Body)
+	}
 
 	headers := js.Global.Get("Headers").New()
 	for header, values := range req.Headers {
@@ -71,5 +68,5 @@ func Fetch(req Request) (Response, error) {
 
 	promise := js.Global.Call("fetch", req.URL.String(), init)
 	promise.Call("then", cb)
-	return Response{}, nil
+	return &Response{}, nil
 }

fetch/fetch/method_string.go

@@ -0,0 +1,16 @@
+// Code generated by "stringer -type Method"; DO NOT EDIT.
+
+package fetch
+
+import "strconv"
+
+const _Method_name = "GETHEADPOSTPUTDELETECONNECTOPTIONSTRACEPATCH"
+
+var _Method_index = [...]uint8{0, 3, 7, 11, 14, 20, 27, 34, 39, 44}
+
+func (i Method) String() string {
+	if i < 0 || i >= Method(len(_Method_index)-1) {
+		return "Method(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Method_name[_Method_index[i]:_Method_index[i+1]]
+}

fetch/main.go

@@ -3,6 +3,8 @@
 package main
 
 import (
+	"bytes"
+	"fmt"
 	"net/http"
 	"net/url"
 
@@ -12,15 +14,15 @@ import (
 func main() {
 	headers := http.Header{}
 	headers.Add("Content-Type", "application/json")
-	req := fetch.Request{
+	req := &fetch.Request{
 		URL: &url.URL{
 			Scheme: "http",
 			Host:   "httpbin.org",
 			Path:   "anything",
 		},
 		Method:  fetch.POST,
-		Body:    []byte(`{"key": "value"}`),
+		Body:    bytes.NewBuffer([]byte(`{"key": "value"}`)),
 		Headers: headers,
 	}
-	fetch.Fetch(req)
+	fmt.Println(fetch.Fetch(req))
 }