Fix handling of absolute schema URLs (#42)

README.md

@@ -41,11 +41,22 @@ import (
 )
 
 func main() {
-	http.Handle("/", v5emb.NewHandler("My API", "/swagger.json", "/"))
-	_ = http.ListenAndServe(":8080", nil)
+	http.Handle("/api1/docs/", v5emb.New(
+		"Petstore",
+		"https://petstore3.swagger.io/api/v3/openapi.json",
+		"/api1/docs/",
+	))
+
+	http.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {
+		_, _ = writer.Write([]byte("Hello World!"))
+	})
+
+	println("docs at http://localhost:8080/api1/docs/")
+	_ = http.ListenAndServe("localhost:8080", http.DefaultServeMux)
 }
 ```
 
+
 If you use `go1.16` or later, you can import natively embedded assets with `"github.com/swaggest/swgui/v5emb"`, it may
 help to lower application memory usage.
 

internal/index.tpl.go

@@ -93,7 +93,10 @@ func IndexTpl(assetsBase, faviconBase string, cfg swgui.Config) string {
 <script>
     window.onload = function () {
         var cfg = {{ .ConfigJson }};
-        var url = window.location.protocol + "//" + window.location.host + cfg.swaggerJsonUrl;
+        var url = cfg.swaggerJsonUrl;
+        if (!url.startsWith("https://") && !url.startsWith("http://")) {
+           url = window.location.protocol + "//" + window.location.host + url;
+        }
 
         // Build a system
         var settings = {