only use the designated fragment when pasting html into a RadzenHtmlEditor (#2285)

* only use the designated fragment when pasting html into a RadzenHtmlEditor

* fragment-extraction inlined

---------

Co-authored-by: Martin Roth <[email protected]>

Author: DinuRoth

Radzen.Blazor/wwwroot/Radzen.Blazor.js

@@ -2011,6 +2011,18 @@ window.Radzen = {
       } else if (paste) {
         e.preventDefault();
         var data = e.clipboardData.getData('text/html') || e.clipboardData.getData('text/plain');
+        
+        const startMarker = "<!--StartFragment-->";
+        const endMarker = "<!--EndFragment-->";
+
+        const startIndex = data.indexOf(startMarker);
+        const endIndex = data.indexOf(endMarker);
+
+        // check if the pasted data contains fragment markers
+        if (startIndex != -1 || endIndex != -1 || endIndex > startIndex) {
+            // only paste the fragment
+            data = data.substring(startIndex + startMarker.length, endIndex).trim();
+        }
 
         instance.invokeMethodAsync('OnPaste', data)
           .then(function (html) {