Add normalize whitelist of characters

Author: blakeembrey

package.json

@@ -34,7 +34,7 @@
   "size-limit": [
     {
       "path": "dist/index.js",
-      "limit": "1.7 kB"
+      "limit": "1.75 kB"
     }
   ],
   "jest": {

src/index.spec.ts

@@ -2832,6 +2832,14 @@ describe("path-to-regexp", function() {
       ]);
     });
 
+    it("should not normalize whitelisted characters", function() {
+      const input = "/test/route%2F%25";
+
+      expect(pathToRegexp.normalizePathname(input)).toEqual(
+        "/test/route%2F%25"
+      );
+    });
+
     it("should fix repeated slashes", function() {
       const input = encodeURI("/test///route");
 

src/index.ts

@@ -19,9 +19,20 @@ export interface ParseOptions {
  * slash and normalizes unicode characters to "NFC". When using this method,
  * `decode` should be an identity function so you don't decode strings twice.
  */
-export function normalizePathname(pathname: string) {
-  return decodeURIComponent(pathname)
+export function normalizePathname(
+  pathname: string,
+  whitelist: string | string[] = "%/-."
+) {
+  return pathname
     .replace(/\/+/g, "/")
+    .replace(
+      /(?:%[ef][0-9a-f](?:%[0-9a-f]{2}){2}|%[cd][0-9a-f]%[0-9a-f]{2}|%[0-9a-f]{2})/gi,
+      function(m) {
+        const char = decodeURIComponent(m);
+        if (whitelist.indexOf(char) > -1) return m;
+        return char;
+      }
+    )
     .normalize();
 }