Add Firefox install url

README.md

@@ -4,7 +4,8 @@ Extends the booking portal of bahn.de with linking to useful information.
 ## Installation
 ### Aus Firefox Add-ons (Empfohlen)
 Einfach zu Firefox hinzufügen:
-TBD
+
+https://addons.mozilla.org/firefox/addon/bahn-insight/
 
 ### Als Entwicklerversion
 1. Herunterladen

js/reiseauskunft.js

@@ -129,6 +129,12 @@ var connection_result_observer = new MutationObserver((mutations) => {
 
         var timetable = target.querySelector("td div.detailContainer table.result tbody");
 
+        // Just break if there are elements injected by us
+        if(timetable.querySelectorAll(".bahn-insight").length != 0) {
+          log("links already injected")
+          return;
+        }
+
         /*
          * COLLECT DATA
          */