🧑‍💻 use strict types in js code

page/start/copylink.js

@@ -1,3 +1,5 @@
+"use strict";
+
 window.addEventListener("load", function(event){
 	// REGISTER ONCLICK HANDLERS //
 	// iterate over all copylink buttons

page/start/newsletter.js

@@ -1,3 +1,5 @@
+"use strict";
+
 let newsletter_form;
 let newsletter_input_mail_address;
 let newsletter_input_language;