From b769e0eb6c81796dd50262749f19607dc23be43a Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 6 Jan 2015 22:24:34 +0900
Subject: [PATCH] Update server/main.go to show GopherJS errors

---
 example/server/main.go | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/example/server/main.go b/example/server/main.go
index fe5d16ef6..31ad16aff 100644
--- a/example/server/main.go
+++ b/example/server/main.go
@@ -15,8 +15,10 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
+	"html/template"
 	"io"
 	"io/ioutil"
 	"log"
@@ -61,8 +63,10 @@ func createJSIfNeeded(name string) (string, error) {
 	}
 	if (err != nil && os.IsNotExist(err)) || time.Now().Sub(stat.ModTime()) > 10*time.Second {
 		target := "github.com/hajimehoshi/ebiten/example/" + name
-		if err := exec.Command("gopherjs", "build", "-o", out, target).Run(); err != nil {
-			return "", err
+		out, err := exec.Command("gopherjs", "build", "-o", out, target).CombinedOutput()
+		if err != nil {
+			log.Print(string(out))
+			return "", errors.New(string(out))
 		}
 	}
 	return out, nil
@@ -97,19 +101,22 @@ func appName(r *http.Request) (string, error) {
 func serveMainJS(w http.ResponseWriter, r *http.Request) {
 	name, err := appName(r)
 	if err != nil {
-		w.WriteHeader(http.StatusBadRequest)
-		fmt.Fprint(w, err.Error())
+		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
 	out, err := createJSIfNeeded(name)
 	if err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		fmt.Fprint(w, err.Error())
+		t := template.JSEscapeString(template.HTMLEscapeString(err.Error()))
+		js := `
+window.onload = function() {
+    document.body.innerHTML="<pre style='white-space: pre-wrap;'><code>` + t + `</code></pre>";
+}`
+		w.Header().Set("Content-Type", "text/javascript")
+		fmt.Fprintf(w, js)
 		return
 	}
 	if err := serveFile(w, out, "text/javascript"); err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		fmt.Fprint(w, err.Error())
+		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 }
@@ -117,20 +124,17 @@ func serveMainJS(w http.ResponseWriter, r *http.Request) {
 func serveMainJSMap(w http.ResponseWriter, r *http.Request) {
 	name, err := appName(r)
 	if err != nil {
-		w.WriteHeader(http.StatusBadRequest)
-		fmt.Fprint(w, err.Error())
+		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 	out, err := createJSIfNeeded(name)
 	if err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		fmt.Fprint(w, err.Error())
+		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 	out += ".map"
 	if err := serveFile(w, out, "application/octet-stream"); err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		fmt.Fprint(w, err.Error())
+		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 }