Replace object.fromEntries() with version that works with older JS

Author: kiliman

packages/remix/src/utils/web-fetch.ts

@@ -147,8 +147,7 @@ export const normalizeRemixRequest = (request: RemixRequest): Record<string, any
     query: parsedURL.query,
     href: parsedURL.href,
     method: request.method,
-    // Remix now uses undici, so use standard way to create headers object
-    headers: Object.fromEntries(headers),
+    headers: objectFromHeaders(headers),
     insecureHTTPParser: request.insecureHTTPParser,
     agent,
 
@@ -161,3 +160,35 @@ export const normalizeRemixRequest = (request: RemixRequest): Record<string, any
 
   return requestOptions;
 };
+
+// This function is a `polyfill` for Object.fromEntries()
+function objectFromHeaders(headers: Headers): Record<string, string> {
+  const result: Record<string, string> = {};
+  let iterator: IterableIterator<[string, string]>;
+
+  if (hasIterator(headers)) {
+    iterator = getIterator(headers) as IterableIterator<[string, string]>;
+  } else {
+    return {};
+  }
+
+  for (const [key, value] of iterator) {
+    result[key] = value;
+  }
+  return result;
+}
+
+type IterableType<T> = {
+  [Symbol.iterator]: () => Iterator<T>;
+};
+
+function hasIterator<T>(obj: T): obj is T & IterableType<unknown> {
+  return obj !== null && typeof (obj as IterableType<unknown>)[Symbol.iterator] === 'function';
+}
+
+function getIterator<T>(obj: T): Iterator<unknown> {
+  if (hasIterator(obj)) {
+    return (obj as IterableType<unknown>)[Symbol.iterator]();
+  }
+  throw new Error('Object does not have an iterator');
+}