Correct "copy" src block function

js/script.js

@@ -32,8 +32,10 @@ docReady(function() {
     let srcContainers = document.querySelectorAll('pre.src');
 
     function copyClickFunction() {
+        let boxCopy = this;
+
         // Create a clone the node to not affect the original one
-        let nodeClone = this.parentNode.cloneNode(true);
+        let nodeClone = boxCopy.parentNode.cloneNode(true);
 
         // Remove Line Numbers and Copy Button
         let linenumNodes = nodeClone.querySelectorAll('.linenr,.src-copy');