fix(react-router-dom): fix getSearchParamsForLocation in Firefox

.changeset/firefox-addons-and-web-extensions-bug.md

@@ -0,0 +1,5 @@
+---
+"react-router-dom": patch
+---
+
+Fixes an edge-case affecting web extensions in Firefox that use `URLSearchParams` and the `useSearchParams` hook.

contributors.yml

@@ -219,3 +219,4 @@
 - yuleicul
 - zheng-chuang
 - holynewbie
+- smithki

packages/react-router-dom/dom.ts

@@ -97,13 +97,18 @@ export function getSearchParamsForLocation(
   let searchParams = createSearchParams(locationSearch);
 
   if (defaultSearchParams) {
-    for (let key of defaultSearchParams.keys()) {
+    // Use `defaultSearchParams.forEach(...)` here instead of iterating of
+    // `defaultSearchParams.keys()` to work-around a bug in Firefox related to
+    // web extensions. Relevant Bugzilla tickets:
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1414602
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1023984
+    defaultSearchParams.forEach((_, key) => {
       if (!searchParams.has(key)) {
         defaultSearchParams.getAll(key).forEach((value) => {
           searchParams.append(key, value);
         });
       }
-    }
+    });
   }
 
   return searchParams;