perf: reduce bundle size by another 26 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 `847 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 `821 bytes` added to your bundle).
 
 ## Installation
 

src/index.ts

@@ -22,9 +22,6 @@ 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,
   (arr: undefined | null): undefined,
@@ -85,37 +82,40 @@ export const createCors = ({
   const joinedAllowHeaders = stringArrayJoinWithComma(optsAllowHeaders);
 
   return async (request: Request, response: Response): Promise<Response> => {
-    const originHeaderValue = getHeader(request, ORIGIN) || '';
+    const setHeader = (name: string, value: string) => response[HEADERS_].set(name, value);
+    const getHeader = (name: string) => request[HEADERS_].get(name);
+
+    const originHeaderValue = getHeader(ORIGIN) || '';
     const allowOrigin = await findAllowOrigin(originHeaderValue);
     if (allowOrigin) {
-      setHeader(response, ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + ORIGIN, allowOrigin);
+      setHeader(ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + ORIGIN, allowOrigin);
     }
     // Suppose the server sends a response with an Access-Control-Allow-Origin value with an explicit origin (rather than the "*" wildcard).
     // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin
     if (shouldVaryIncludeOrigin) {
-      setHeader(response, VARY, getHeader(request, VARY) /** existing Vary */ || ORIGIN);
+      setHeader(VARY, getHeader(VARY) /** existing Vary */ || ORIGIN);
     }
     if (optsCredentials) {
-      setHeader(response, ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + 'Credentials', '' + optsCredentials);
+      setHeader(ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + 'Credentials', '' + optsCredentials);
     }
     if (exposeHeaders) {
-      setHeader(response, ACCESS_CONTROL_PREFIX + 'Expose-' + HEADERS, exposeHeaders);
+      setHeader(ACCESS_CONTROL_PREFIX + 'Expose-' + HEADERS, exposeHeaders);
     }
 
     if (request.method === 'OPTIONS') {
       if (optsMaxAge != null) {
-        setHeader(response, ACCESS_CONTROL_PREFIX + 'Max-Age', '' + optsMaxAge);
+        setHeader(ACCESS_CONTROL_PREFIX + 'Max-Age', '' + optsMaxAge);
       }
 
       const allowMethods = await findAllowMethods(originHeaderValue);
       if (allowMethods.length) {
-        setHeader(response, ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + 'Methods', stringArrayJoinWithComma(allowMethods));
+        setHeader(ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + 'Methods', stringArrayJoinWithComma(allowMethods));
       }
 
       const ACCESS_CONTROL_REQUEST_HEADERS = ACCESS_CONTROL_PREFIX + 'Request-' + HEADERS;
-      const allowHeader = joinedAllowHeaders || getHeader(request, ACCESS_CONTROL_REQUEST_HEADERS);
+      const allowHeader = joinedAllowHeaders || getHeader(ACCESS_CONTROL_REQUEST_HEADERS);
       if (allowHeader) {
-        setHeader(response, ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + HEADERS, allowHeader);
+        setHeader(ACCESS_CONTROL_PREFIX + ALLOW_PREFIX + HEADERS, allowHeader);
         response[HEADERS_].append(VARY, ACCESS_CONTROL_REQUEST_HEADERS);
       }
     }