perf: avoid redundant work in redactSensitiveHeaders on each call (#113)

Move headersWithSensitiveUrlsLowered and redactSensitiveKeys outside
the inner closure so they are computed once at initialization time
rather than on every invocation of redactSensitiveHeaders.

Author: melikhov-dev

src/lib/utils/redact-sensitive-headers.ts

@@ -10,17 +10,16 @@ export default function prepareSensitiveHeadersRedacter(
     redactSensitiveQueryParams: (input: string) => string = (input) => input,
     isDevMode = false,
 ) {
+    const headersWithSensitiveUrlsLowered = headersWithSensitiveUrls.map((name) =>
+        name.toLowerCase(),
+    );
+    const redactSensitiveKeys = prepareSensitiveKeysRedacter(sensitiveHeaders);
+
     const redactSensitiveHeaders: SensitiveHeadersRedacter = (inputHeaders = {}) => {
         if (isDevMode) {
             return inputHeaders;
         }
 
-        const headersWithSensitiveUrlsLowered = headersWithSensitiveUrls.map((name) =>
-            name.toLowerCase(),
-        );
-
-        const redactSensitiveKeys = prepareSensitiveKeysRedacter(sensitiveHeaders);
-
         const result = redactSensitiveKeys(inputHeaders) as IncomingHttpHeaders;
 
         Object.keys(result).forEach((headerName) => {