diff --git a/examples/r2-image-server/Makefile b/examples/r2-image-server/Makefile
new file mode 100644
index 0000000..320ddc3
--- /dev/null
+++ b/examples/r2-image-server/Makefile
@@ -0,0 +1,12 @@
+.PHONY: dev
+dev:
+	wrangler dev
+
+.PHONY: build
+build:
+	mkdir -p dist
+	tinygo build -o ./dist/app.wasm -target wasm ./...
+
+.PHONY: publish
+publish:
+	wrangler publish
diff --git a/examples/r2-image-server/README.md b/examples/r2-image-server/README.md
new file mode 100644
index 0000000..9bd46df
--- /dev/null
+++ b/examples/r2-image-server/README.md
@@ -0,0 +1,52 @@
+# simple-json-server
+
+* A simple HTTP JSON server implemented in Go and compiled with tinygo.
+
+## Example
+
+* https://simple-json-server.syumai.workers.dev
+
+### Request
+
+```
+curl --location --request POST 'https://simple-json-server.syumai.workers.dev/hello' \
+--header 'Content-Type: application/json' \
+--data-raw '{
+    "name": "syumai"
+}'
+```
+
+### Response
+
+```json
+{
+    "message": "Hello, syumai!"
+}
+```
+
+## Development
+
+### Requirements
+
+This project requires these tools to be installed globally.
+
+* wrangler
+* tinygo
+* [easyjson](https://github.com/mailru/easyjson)
+  - `go install github.com/mailru/easyjson/...@latest`
+
+### Commands
+
+```
+make dev     # run dev server
+make build   # build Go Wasm binary
+make publish # publish worker
+```
+
+## Author
+
+syumai
+
+## License
+
+MIT
diff --git a/examples/r2-image-server/go.mod b/examples/r2-image-server/go.mod
new file mode 100644
index 0000000..9926cb2
--- /dev/null
+++ b/examples/r2-image-server/go.mod
@@ -0,0 +1,7 @@
+module github.com/syumai/workers/examples/r2-image-server
+
+go 1.18
+
+require github.com/syumai/workers v0.0.0-00010101000000-000000000000
+
+replace github.com/syumai/workers => ../../
diff --git a/examples/r2-image-server/go.sum b/examples/r2-image-server/go.sum
new file mode 100644
index 0000000..e69de29
diff --git a/examples/r2-image-server/jsutil.go b/examples/r2-image-server/jsutil.go
new file mode 100644
index 0000000..d80a77a
--- /dev/null
+++ b/examples/r2-image-server/jsutil.go
@@ -0,0 +1,100 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"syscall/js"
+	"time"
+)
+
+var (
+	global              = js.Global()
+	objectClass         = global.Get("Object")
+	promiseClass        = global.Get("Promise")
+	uint8ArrayClass     = global.Get("Uint8Array")
+	errorClass          = global.Get("Error")
+	readableStreamClass = global.Get("ReadableStream")
+	stringClass         = global.Get("String")
+)
+
+func newObject() js.Value {
+	return objectClass.New()
+}
+
+func newUint8Array(size int) js.Value {
+	return uint8ArrayClass.New(size)
+}
+
+func newPromise(fn js.Func) js.Value {
+	return promiseClass.New(fn)
+}
+
+func awaitPromise(promiseVal js.Value) (js.Value, error) {
+	resultCh := make(chan js.Value)
+	errCh := make(chan error)
+	var then, catch js.Func
+	then = js.FuncOf(func(_ js.Value, args []js.Value) any {
+		defer then.Release()
+		result := args[0]
+		resultCh <- result
+		return js.Undefined()
+	})
+	catch = js.FuncOf(func(_ js.Value, args []js.Value) any {
+		defer catch.Release()
+		result := args[0]
+		errCh <- fmt.Errorf("failed on promise: %s", result.Call("toString").String())
+		return js.Undefined()
+	})
+	promiseVal.Call("then", then).Call("catch", catch)
+	select {
+	case result := <-resultCh:
+		return result, nil
+	case err := <-errCh:
+		return js.Value{}, err
+	}
+}
+
+// dateToTime converts JavaScript side's Data object into time.Time.
+func dateToTime(v js.Value) (time.Time, error) {
+	milliStr := stringClass.Invoke(v.Call("getTime")).String()
+	milli, err := strconv.ParseInt(milliStr, 10, 64)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("failed to convert Date to time.Time: %w", err)
+	}
+	return time.UnixMilli(milli), nil
+}
+
+// strRecordToMap converts JavaScript side's Record<string, string> into map[string]string.
+func strRecordToMap(v js.Value) map[string]string {
+	entries := objectClass.Call("entries", v)
+	entriesLen := entries.Get("length").Int()
+	result := make(map[string]string, entriesLen)
+	for i := 0; i < entriesLen; i++ {
+		entry := entries.Index(i)
+		key := entry.Index(0).String()
+		value := entry.Index(1).String()
+		result[key] = value
+	}
+	return result
+}
+
+// maybeString returns string value of given JavaScript value or returns nil if the value is undefined.
+func maybeString(v js.Value) *string {
+	if v.IsUndefined() {
+		return nil
+	}
+	s := v.String()
+	return &s
+}
+
+// maybeDate returns time.Time value of given JavaScript Date value or returns nil if the value is undefined.
+func maybeDate(v js.Value) (*time.Time, error) {
+	if v.IsUndefined() {
+		return nil, nil
+	}
+	d, err := dateToTime(v)
+	if err != nil {
+		return nil, err
+	}
+	return &d, nil
+}
diff --git a/examples/r2-image-server/main.go b/examples/r2-image-server/main.go
new file mode 100644
index 0000000..d825e6e
--- /dev/null
+++ b/examples/r2-image-server/main.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"strings"
+
+	"github.com/syumai/workers"
+)
+
+// bucketName is R2 bucket name defined in wrangler.toml.
+const bucketName = "BUCKET"
+
+func handleErr(w http.ResponseWriter, msg string, err error) {
+	log.Println(err)
+	w.WriteHeader(http.StatusInternalServerError)
+	w.Write([]byte(msg))
+}
+
+// This example is based on implementation in syumai/workers-playground
+// * https://github.com/syumai/workers-playground/blob/e32881648ccc055e3690a0d9c750a834261c333e/r2-image-viewer/src/index.ts#L30
+func handler(w http.ResponseWriter, req *http.Request) {
+	bucket, err := NewR2Bucket(bucketName)
+	if err != nil {
+		handleErr(w, "failed to get R2Bucket\n", err)
+		return
+	}
+	imgPath := strings.TrimPrefix(req.URL.Path, "/")
+	imgObj, err := bucket.Get(imgPath)
+	if err != nil {
+		handleErr(w, "failed to get R2Object\n", err)
+		return
+	}
+	if imgObj == nil {
+		w.WriteHeader(http.StatusNotFound)
+		w.Write([]byte(fmt.Sprintf("image not found: %s", imgPath)))
+		return
+	}
+	w.Header().Set("Cache-Control", "public, max-age=14400")
+	w.Header().Set("ETag", fmt.Sprintf("W/%s", imgObj.HTTPETag))
+	contentType := "application/octet-stream"
+	if imgObj.HTTPMetadata.ContentType != nil {
+		contentType = *imgObj.HTTPMetadata.ContentType
+	}
+	w.Header().Set("Content-Type", contentType)
+	io.Copy(w, imgObj.Body)
+}
+
+func main() {
+	workers.Serve(http.HandlerFunc(handler))
+}
diff --git a/examples/r2-image-server/r2bucket.go b/examples/r2-image-server/r2bucket.go
new file mode 100644
index 0000000..96511b0
--- /dev/null
+++ b/examples/r2-image-server/r2bucket.go
@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"syscall/js"
+)
+
+// R2Bucket represents interface of Cloudflare Worker's R2 Bucket instance.
+// - https://developers.cloudflare.com/r2/runtime-apis/#bucket-method-definitions
+// - https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1006
+type R2Bucket interface {
+	Head(key string) (*R2Object, error)
+	Get(key string) (*R2Object, error)
+	Put(key string, value io.Reader) error
+	Delete(key string) error
+	List() (*R2Objects, error)
+}
+
+type r2Bucket struct {
+	instance js.Value
+}
+
+var _ R2Bucket = &r2Bucket{}
+
+func (r *r2Bucket) Head(key string) (*R2Object, error) {
+	p := r.instance.Call("head", key)
+	v, err := awaitPromise(p)
+	if err != nil {
+		return nil, err
+	}
+	if v.IsNull() {
+		return nil, nil
+	}
+	return toR2Object(v)
+}
+
+func (r *r2Bucket) Get(key string) (*R2Object, error) {
+	p := r.instance.Call("get", key)
+	v, err := awaitPromise(p)
+	if err != nil {
+		return nil, err
+	}
+	fmt.Println(v)
+	if v.IsNull() {
+		return nil, nil
+	}
+	return toR2Object(v)
+}
+
+func (r *r2Bucket) Put(key string, value io.Reader) error {
+	panic("implement me")
+}
+
+func (r *r2Bucket) Delete(key string) error {
+	panic("implement me")
+}
+
+func (r *r2Bucket) List() (*R2Objects, error) {
+	p := r.instance.Call("list")
+	v, err := awaitPromise(p)
+	if err != nil {
+		return nil, err
+	}
+	return toR2Objects(v)
+}
+
+func NewR2Bucket(varName string) (R2Bucket, error) {
+	inst := js.Global().Get(varName)
+	if inst.IsUndefined() {
+		return nil, fmt.Errorf("%s is undefined", varName)
+	}
+	return &r2Bucket{instance: inst}, nil
+}
diff --git a/examples/r2-image-server/r2object.go b/examples/r2-image-server/r2object.go
new file mode 100644
index 0000000..26e97b1
--- /dev/null
+++ b/examples/r2-image-server/r2object.go
@@ -0,0 +1,95 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"syscall/js"
+	"time"
+)
+
+// R2Object represents JavaScript side's R2Object.
+// * https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1094
+type R2Object struct {
+	instance       js.Value
+	Key            string
+	Version        string
+	Size           int
+	ETag           string
+	HTTPETag       string
+	Uploaded       time.Time
+	HTTPMetadata   R2HTTPMetadata
+	CustomMetadata map[string]string
+	// Body is a body of R2Object.
+	// This value becomes nil when `Head` method of R2Bucket is called.
+	Body io.Reader
+}
+
+// TODO: implement
+// - https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1106
+// func (o *R2Object) WriteHTTPMetadata(headers http.Header) {
+// }
+
+func (o *R2Object) BodyUsed() (bool, error) {
+	v := o.instance.Get("bodyUsed")
+	if v.IsUndefined() {
+		return false, errors.New("bodyUsed doesn't exist for this R2Object")
+	}
+	return v.Bool(), nil
+}
+
+// toR2Object converts JavaScript side's R2Object to *R2Object.
+// * https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1094
+func toR2Object(v js.Value) (*R2Object, error) {
+	uploaded, err := dateToTime(v.Get("uploaded"))
+	if err != nil {
+		return nil, fmt.Errorf("error converting uploaded: %w", err)
+	}
+	r2Meta, err := toR2HTTPMetadata(v.Get("httpMetadata"))
+	if err != nil {
+		return nil, fmt.Errorf("error converting httpMetadata: %w", err)
+	}
+	bodyVal := v.Get("body")
+	var body io.Reader
+	if !bodyVal.IsUndefined() {
+		body = convertStreamReaderToReader(v.Get("body").Call("getReader"))
+	}
+	return &R2Object{
+		instance:       v,
+		Key:            v.Get("key").String(),
+		Version:        v.Get("version").String(),
+		Size:           v.Get("size").Int(),
+		ETag:           v.Get("etag").String(),
+		HTTPETag:       v.Get("httpEtag").String(),
+		Uploaded:       uploaded,
+		HTTPMetadata:   r2Meta,
+		CustomMetadata: strRecordToMap(v.Get("customMetadata")),
+		Body:           body,
+	}, nil
+}
+
+// R2HTTPMetadata represents metadata of R2 Object.
+// * https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1053
+type R2HTTPMetadata struct {
+	ContentType        *string
+	ContentLanguage    *string
+	ContentDisposition *string
+	ContentEncoding    *string
+	CacheControl       *string
+	CacheExpiry        *time.Time
+}
+
+func toR2HTTPMetadata(v js.Value) (R2HTTPMetadata, error) {
+	cacheExpiry, err := maybeDate(v.Get("cacheExpiry"))
+	if err != nil {
+		return R2HTTPMetadata{}, fmt.Errorf("error converting cacheExpiry: %w", err)
+	}
+	return R2HTTPMetadata{
+		ContentType:        maybeString(v.Get("contentType")),
+		ContentLanguage:    maybeString(v.Get("contentLanguage")),
+		ContentDisposition: maybeString(v.Get("contentDisposition")),
+		ContentEncoding:    maybeString(v.Get("contentEncoding")),
+		CacheControl:       maybeString(v.Get("cacheControl")),
+		CacheExpiry:        cacheExpiry,
+	}, nil
+}
diff --git a/examples/r2-image-server/r2objects.go b/examples/r2-image-server/r2objects.go
new file mode 100644
index 0000000..f6bac6b
--- /dev/null
+++ b/examples/r2-image-server/r2objects.go
@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"syscall/js"
+)
+
+// R2Objects represents JavaScript side's R2Objects.
+// * https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1121
+type R2Objects struct {
+	Objects           []*R2Object
+	Truncated         bool
+	Cursor            *string
+	DelimitedPrefixes []string
+}
+
+// toR2Objects converts JavaScript side's R2Objects to *R2Objects.
+// * https://github.com/cloudflare/workers-types/blob/3012f263fb1239825e5f0061b267c8650d01b717/index.d.ts#L1121
+func toR2Objects(v js.Value) (*R2Objects, error) {
+	objectsVal := v.Get("objects")
+	objects := make([]*R2Object, objectsVal.Length())
+	for i := 0; i < len(objects); i++ {
+		obj, err := toR2Object(objectsVal.Index(i))
+		if err != nil {
+			return nil, fmt.Errorf("error converting to R2Object: %w", err)
+		}
+		objects[i] = obj
+	}
+	prefixesVal := objectsVal.Get("delimitedPrefixes")
+	prefixes := make([]string, prefixesVal.Length())
+	for i := 0; i < len(prefixes); i++ {
+		prefixes[i] = prefixesVal.Index(i).String()
+	}
+	return &R2Objects{
+		Objects:           objects,
+		Truncated:         objectsVal.Get("truncated").Bool(),
+		Cursor:            maybeString(objectsVal.Get("cursor")),
+		DelimitedPrefixes: prefixes,
+	}, nil
+}
diff --git a/examples/r2-image-server/stream.go b/examples/r2-image-server/stream.go
new file mode 100644
index 0000000..fa0a525
--- /dev/null
+++ b/examples/r2-image-server/stream.go
@@ -0,0 +1,140 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"syscall/js"
+)
+
+// streamReaderToReader implements io.Reader sourced from ReadableStreamDefaultReader.
+// * ReadableStreamDefaultReader: https://developer.mozilla.org/en-US/docs/Web/API/ReadableStreamDefaultReader
+// * This implementation is based on: https://deno.land/std@0.139.0/streams/conversion.ts#L76
+type streamReaderToReader struct {
+	buf          bytes.Buffer
+	streamReader js.Value
+}
+
+// Read reads bytes from ReadableStreamDefaultReader.
+func (sr *streamReaderToReader) Read(p []byte) (n int, err error) {
+	if sr.buf.Len() == 0 {
+		promise := sr.streamReader.Call("read")
+		resultCh := make(chan js.Value)
+		errCh := make(chan error)
+		var then, catch js.Func
+		then = js.FuncOf(func(_ js.Value, args []js.Value) any {
+			defer then.Release()
+			result := args[0]
+			if result.Get("done").Bool() {
+				errCh <- io.EOF
+				return js.Undefined()
+			}
+			resultCh <- result.Get("value")
+			return js.Undefined()
+		})
+		catch = js.FuncOf(func(_ js.Value, args []js.Value) any {
+			defer catch.Release()
+			result := args[0]
+			errCh <- fmt.Errorf("JavaScript error on read: %s", result.Call("toString").String())
+			return js.Undefined()
+		})
+		promise.Call("then", then).Call("catch", catch)
+		select {
+		case result := <-resultCh:
+			chunk := make([]byte, result.Get("byteLength").Int())
+			_ = js.CopyBytesToGo(chunk, result)
+			// The length written is always the same as the length of chunk, so it can be discarded.
+			// - https://pkg.go.dev/bytes#Buffer.Write
+			_, err := sr.buf.Write(chunk)
+			if err != nil {
+				return 0, err
+			}
+		case err := <-errCh:
+			return 0, err
+		}
+	}
+	return sr.buf.Read(p)
+}
+
+// convertStreamReaderToReader converts ReadableStreamDefaultReader to io.Reader.
+func convertStreamReaderToReader(sr js.Value) io.Reader {
+	return &streamReaderToReader{
+		streamReader: sr,
+	}
+}
+
+// readerToReadableStream implements ReadableStream sourced from io.ReadCloser.
+// * ReadableStream: https://developer.mozilla.org/docs/Web/API/ReadableStream
+// * This implementation is based on: https://deno.land/std@0.139.0/streams/conversion.ts#L230
+type readerToReadableStream struct {
+	reader   io.ReadCloser
+	chunkBuf []byte
+}
+
+// Pull implements ReadableStream's pull method.
+// * https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream/ReadableStream#pull
+func (rs *readerToReadableStream) Pull(controller js.Value) error {
+	n, err := rs.reader.Read(rs.chunkBuf)
+	if err == io.EOF {
+		if err := rs.reader.Close(); err != nil {
+			return err
+		}
+		controller.Call("close")
+		return nil
+	}
+	if err != nil {
+		jsErr := errorClass.New(err.Error())
+		controller.Call("error", jsErr)
+		if err := rs.reader.Close(); err != nil {
+			return err
+		}
+		return err
+	}
+	ua := newUint8Array(n)
+	_ = js.CopyBytesToJS(ua, rs.chunkBuf[:n])
+	controller.Call("enqueue", ua)
+	return nil
+}
+
+// Cancel implements ReadableStream's cancel method.
+// * https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream/ReadableStream#cancel
+func (rs *readerToReadableStream) Cancel() error {
+	return rs.reader.Close()
+}
+
+// https://deno.land/std@0.139.0/streams/conversion.ts#L5
+const defaultChunkSize = 16_640
+
+// convertReaderToReadableStream converts io.ReadCloser to ReadableStream.
+func convertReaderToReadableStream(reader io.ReadCloser) js.Value {
+	stream := &readerToReadableStream{
+		reader:   reader,
+		chunkBuf: make([]byte, defaultChunkSize),
+	}
+	rsInit := newObject()
+	rsInit.Set("pull", js.FuncOf(func(_ js.Value, args []js.Value) any {
+		var cb js.Func
+		cb = js.FuncOf(func(this js.Value, pArgs []js.Value) any {
+			defer cb.Release()
+			resolve := pArgs[0]
+			reject := pArgs[1]
+			controller := args[0]
+			err := stream.Pull(controller)
+			if err != nil {
+				reject.Invoke(errorClass.New(err.Error()))
+				return js.Undefined()
+			}
+			resolve.Invoke()
+			return js.Undefined()
+		})
+		return newPromise(cb)
+	}))
+	rsInit.Set("cancel", js.FuncOf(func(js.Value, []js.Value) any {
+		err := stream.Cancel()
+		if err != nil {
+			panic(err)
+		}
+		return js.Undefined()
+	}))
+	return readableStreamClass.New(rsInit)
+}
diff --git a/examples/r2-image-server/worker.mjs b/examples/r2-image-server/worker.mjs
new file mode 100644
index 0000000..06ce572
--- /dev/null
+++ b/examples/r2-image-server/worker.mjs
@@ -0,0 +1,19 @@
+import "../assets/polyfill_performance.js";
+import "../assets/wasm_exec.js";
+import mod from "./dist/app.wasm";
+
+const go = new Go();
+
+const load = WebAssembly.instantiate(mod, go.importObject).then((instance) => {
+  go.run(instance);
+  return instance;
+});
+
+async function processRequest(event) {
+  const req = event.request;
+  await load;
+  console.log("finished loading");
+  return handleRequest(req);
+}
+
+addEventListener("fetch", (event) => event.respondWith(processRequest(event)))
diff --git a/examples/r2-image-server/wrangler.toml b/examples/r2-image-server/wrangler.toml
new file mode 100644
index 0000000..b4ab471
--- /dev/null
+++ b/examples/r2-image-server/wrangler.toml
@@ -0,0 +1,14 @@
+name = "r2-image-server"
+main = "./worker.mjs"
+compatibility_date = "2022-05-13"
+compatibility_flags = [
+    "streams_enable_constructors"
+]
+
+[build]
+command = "make build"
+
+[[r2_buckets]]
+binding = 'BUCKET'
+bucket_name = 'r2-image-viewer'
+preview_bucket_name = 'r2-image-viewer-dev'
\ No newline at end of file