From 251c037f424ace09e87ec0a47d7579d7b90626a1 Mon Sep 17 00:00:00 2001
From: Jake Champion <me@jakechampion.name>
Date: Thu, 25 Jan 2024 19:56:20 +0000
Subject: [PATCH] fix: If request does not have a static backend defined,
 return `undefined` for the Request.prototype.backend getter (#722)

---
 runtime/js-compute-runtime/builtins/request-response.cpp | 6 +-----
 types/globals.d.ts                                       | 2 +-
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/runtime/js-compute-runtime/builtins/request-response.cpp b/runtime/js-compute-runtime/builtins/request-response.cpp
index 56e8afb4fa..e035920b8c 100644
--- a/runtime/js-compute-runtime/builtins/request-response.cpp
+++ b/runtime/js-compute-runtime/builtins/request-response.cpp
@@ -1263,11 +1263,7 @@ bool Request::bodyAll(JSContext *cx, unsigned argc, JS::Value *vp) {
 bool Request::backend_get(JSContext *cx, unsigned argc, JS::Value *vp) {
   METHOD_HEADER(0)
   JS::RootedValue backend(cx, JS::GetReservedSlot(self, static_cast<uint32_t>(Slots::Backend)));
-  if (backend.isNullOrUndefined()) {
-    args.rval().setString(JS_GetEmptyString(cx));
-  } else {
-    args.rval().set(backend);
-  }
+  args.rval().set(backend);
 
   return true;
 }
diff --git a/types/globals.d.ts b/types/globals.d.ts
index c88cbb5ca0..42a53b6fb4 100644
--- a/types/globals.d.ts
+++ b/types/globals.d.ts
@@ -1084,7 +1084,7 @@ interface Request extends Body {
   clone(): Request;
 
   // Fastly extensions
-  backend: string;
+  backend?: string;
   setCacheOverride(override: import('fastly:cache-override').CacheOverride): void;
   setCacheKey(key: string): void;
   setManualFramingHeaders(manual: boolean): void;