Fix request.cf.clientAcceptEncoding type to string, closes #362

Author: mrbbot

packages/core/src/standards/cf.ts

@@ -26,7 +26,7 @@ export interface IncomingRequestCfProperties {
   asn: number;
   botManagement?: IncomingRequestCfPropertiesBotManagement;
   city?: string;
-  clientAcceptEncoding?: string | string[];
+  clientAcceptEncoding?: string;
   clientTcpRtt: number;
   clientTrustScore?: number;
   colo: string;

packages/http-server/src/index.ts

@@ -114,9 +114,12 @@ export async function convertNodeRequest(
   req.headers["cf-visitor"] ??= `{"scheme":"${proto}"}`;
   req.headers["host"] = url.host;
 
-  // Keep it to use later
+  // Store original `Accept-Encoding` for `request.cf.clientAcceptEncoding`
   const clientAcceptEncoding = req.headers["accept-encoding"];
-  // This should be fixed
+  // Only the `Set-Cookie` header is an array: https://nodejs.org/api/http.html#messageheaders
+  assert(!Array.isArray(clientAcceptEncoding));
+  // The Workers runtime will always set `Accept-Encoding` to `gzip`:
+  // https://github.com/cloudflare/miniflare/issues/180
   req.headers["accept-encoding"] = "gzip";
 
   // Build Headers object from request