perf: reduce bundle size by another 16 bytes

Author: SukkaW

README.md

@@ -1,6 +1,6 @@
 # cors-edge
 
-You are writing a very simple functions that runs on edge (either on Cloudflare Workers, Fastly Edge Compute, Vercel Edge Functions, etc.) consisting of less than 100 lines of code. You want to enable CORS (Cross-Origin Resource Sharing) for your endpoint but you do not want to pull in a heavy framework with middlewares just for that. This platform-agnostic package provides a simple way to add CORS support with minimal footprint (with only `924 bytes` added to your bundle).
+You are writing a very simple functions that runs on edge (either on Cloudflare Workers, Fastly Edge Compute, Vercel Edge Functions, etc.) consisting of less than 100 lines of code. You want to enable CORS (Cross-Origin Resource Sharing) for your endpoint but you do not want to pull in a heavy framework with middlewares just for that. This platform-agnostic package provides a simple way to add CORS support with minimal footprint (with only `908 bytes` added to your bundle).
 
 ## Installation
 

src/index.ts

@@ -18,8 +18,12 @@ const VARY = 'Vary';
 const ORIGIN = 'Origin';
 const HEADERS = 'Headers';
 
-const setHeader = (response: Response, name: string, value: string) => response.headers.set(name, value);
-const getHeader = (request: Request, name: string) => request.headers.get(name);
+const { isArray } = Array;
+
+const HEADERS_ = 'headers' as const;
+
+const setHeader = (response: Response, name: string, value: string) => response[HEADERS_].set(name, value);
+const getHeader = (request: Request, name: string) => request[HEADERS_].get(name);
 
 interface StringArrayJoinWithComma {
   (arr: string[]): string,
@@ -60,18 +64,18 @@ export const createCors = ({
     } else {
       findAllowOrigin = (origin: string) => (optsOrigin === origin ? origin : null);
     }
-  } else if (typeof optsOrigin === 'function') {
-    findAllowOrigin = optsOrigin;
-  } else {
+  } else if (isArray(optsOrigin)) {
     const allowedOrigins = new Set(optsOrigin);
     findAllowOrigin = (origin: string) => (allowedOrigins.has(origin) ? origin : null);
+  } else {
+    findAllowOrigin = optsOrigin;
   }
 
   let findAllowMethods: (origin: string) => Promise<string[]> | string[];
-  if (typeof optsAllowMethods === 'function') {
-    findAllowMethods = optsAllowMethods;
-  } else if (Array.isArray(optsAllowMethods)) {
+  if (isArray(optsAllowMethods)) {
     findAllowMethods = () => optsAllowMethods;
+  } else if (typeof optsAllowMethods === 'function') {
+    findAllowMethods = optsAllowMethods;
   } else {
     findAllowMethods = () => [];
   }
@@ -118,14 +122,8 @@ export const createCors = ({
       const allowHeader = joinedAllowHeaders || getHeader(request, ACCESS_CONTROL_REQUEST_HEADERS);
       if (allowHeader) {
         setHeader(response, ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + HEADERS, allowHeader);
-        response.headers.append(VARY, ACCESS_CONTROL_REQUEST_HEADERS);
+        response[HEADERS_].append(VARY, ACCESS_CONTROL_REQUEST_HEADERS);
       }
-
-      // return new Response(null, {
-      //   headers: c.res.headers,
-      //   status: 204,
-      //   statusText: 'No Content'
-      // });
     }
 
     return response;