fix(client): add doctype to preview iframe (freeCodeCamp#57041)

lasjorg · ojeytonwilliams · web-flow · commit 495006f8ab7b · 2024-11-07T14:28:44.000-08:00
Co-authored-by: Oliver Eyton-Williams &lt;ojeytonwilliams@gmail.com&gt;
diff --git a/client/src/templates/Challenges/utils/frame.ts b/client/src/templates/Challenges/utils/frame.ts
@@ -378,8 +378,11 @@ function writeToFrame(content: string, frame?: FrameDocument) {
 }
 
 const writeContentToFrame = (frameContext: Context) => {
+  const doctype =
+    frameContext.sources.contents?.match(/^<!DOCTYPE html>/i)?.[0] || '';
+
   writeToFrame(
-    createHeader(frameContext.element.id) + frameContext.build,
+    doctype + createHeader(frameContext.element.id) + frameContext.build,
     frameContext.document
   );
 
