Add dynamic CORS headers

telegram-bot-proxy.js

@@ -129,29 +129,37 @@ async function handleRequest(request) {
   });
 
   try {
-    const tgRes = await fetch(proxyReq);
-    const res = new Response(tgRes.body, tgRes); // Copy response as-is
-    res.headers.set('Access-Control-Allow-Origin', '*');
-    res.headers.set('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
-    res.headers.set('Access-Control-Allow-Headers', 'Content-Type');
-    return res;
+    const tgRes = await fetch(proxyReq);
+    const res = new Response(tgRes.body, tgRes); // Copy response as-is
+    const reqAllowHeaders = request.headers.get('Access-Control-Request-Headers');
+    const allowHeaders = reqAllowHeaders ? reqAllowHeaders : 'Content-Type';
+    res.headers.set('Access-Control-Allow-Origin', '*');
+    res.headers.set(
+      'Access-Control-Allow-Methods',
+      'GET, POST, PUT, DELETE, OPTIONS, HEAD'
+    );
+    res.headers.set('Access-Control-Allow-Headers', allowHeaders);
+    return res;
   } catch (err) {
     return new Response(`Error proxying request: ${err.message}`, { status: 500 });
   }
 }
 // Handle OPTIONS requests for CORS
-function handleOptions(request) {
-  const corsHeaders = {
-    'Access-Control-Allow-Origin': '*',
-    'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
-    'Access-Control-Allow-Headers': 'Content-Type',
-    'Access-Control-Max-Age': '86400',
-  };
-
-  return new Response(null, {
-    status: 204,
-    headers: corsHeaders,
-  });
+function handleOptions(request) {
+  const reqAllowHeaders = request.headers.get('Access-Control-Request-Headers');
+  const allowHeaders = reqAllowHeaders ? reqAllowHeaders : 'Content-Type';
+
+  const corsHeaders = {
+    'Access-Control-Allow-Origin': '*',
+    'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS, HEAD',
+    'Access-Control-Allow-Headers': allowHeaders,
+    'Access-Control-Max-Age': '86400',
+  };
+
+  return new Response(null, {
+    status: 204,
+    headers: corsHeaders,
+  });
 }
 
 // Main event listener for the worker