refactor(http): Improves base64 encoding/decoding with feature detection (#67002)

SkyZeroZx · thePunderWoman · commit aafeb1d2bd94 · 2026-03-04T15:56:59.000Z
Use feature detection for `Uint8Array.prototype.toBase64` and `Uint8Array.fromBase64`, falling back to the existing implementation when native support is not available PR Close #67002
diff --git a/packages/common/http/src/transfer_cache.ts b/packages/common/http/src/transfer_cache.ts
@@ -29,6 +29,7 @@ import {HTTP_ROOT_INTERCEPTOR_FNS, HttpHandlerFn} from './interceptor';
 import {HttpRequest} from './request';
 import {HttpEvent, HttpResponse} from './response';
 import {HttpParams} from './params';
+import {fromBase64, toBase64} from './util';
 
 /**
  * Options to configure how TransferCache should be used to cache requests made via HttpClient.
@@ -272,7 +273,7 @@ export function transferCacheInterceptorFn(
           transferState.set<TransferHttpResponse>(storeKey, {
             [BODY]:
               req.responseType === 'arraybuffer' || req.responseType === 'blob'
-                ? toBase64(event.body)
+                ? toBase64(event.body as ArrayBufferLike)
                 : event.body,
             [HEADERS]: getFilteredHeaders(event.headers, headersToInclude),
             [STATUS]: event.status,
@@ -360,28 +361,6 @@ function generateHash(value: string): string {
   return hash.toString();
 }
 
-function toBase64(buffer: unknown): string {
-  //TODO: replace with when is Baseline widely available
-  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array/toBase64
-  const bytes = new Uint8Array(buffer as ArrayBufferLike);
-
-  const CHUNK_SIZE = 0x8000; // 32,768 bytes (~32 KB) per chunk, to avoid stack overflow
-
-  let binaryString = '';
-
-  for (let i = 0; i < bytes.length; i += CHUNK_SIZE) {
-    const chunk = bytes.subarray(i, i + CHUNK_SIZE);
-    binaryString += String.fromCharCode.apply(null, chunk as unknown as number[]);
-  }
-  return btoa(binaryString);
-}
-
-function fromBase64(base64: string): ArrayBuffer {
-  const binary = atob(base64);
-  const bytes = Uint8Array.from(binary, (c) => c.charCodeAt(0));
-  return bytes.buffer;
-}
-
 /**
  * Returns the DI providers needed to enable HTTP transfer cache.
  *
diff --git a/packages/common/http/src/util.ts b/packages/common/http/src/util.ts
@@ -0,0 +1,47 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+// TODO: Replace this fallback once widely available.
+// See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array/toBase64
+
+type Uint8ArrayWithToBase64 = Uint8Array & {toBase64(): string};
+type Uint8ArrayCtorWithFromBase64 = typeof Uint8Array & {fromBase64(base64: string): Uint8Array};
+
+function hasToBase64(u8: Uint8Array): u8 is Uint8ArrayWithToBase64 {
+  return typeof (u8 as Uint8ArrayWithToBase64).toBase64 === 'function';
+}
+
+function hasFromBase64(ctor: typeof Uint8Array): ctor is Uint8ArrayCtorWithFromBase64 {
+  return typeof (ctor as Uint8ArrayCtorWithFromBase64).fromBase64 === 'function';
+}
+
+export function toBase64(buffer: ArrayBufferLike): string {
+  const bytes = new Uint8Array(buffer);
+
+  if (hasToBase64(bytes)) {
+    return bytes.toBase64();
+  }
+
+  const CHUNK_SIZE = 0x8000; // 32,768 bytes (~32 KB) per chunk, to avoid stack overflow
+  let binaryString = '';
+  for (let i = 0; i < bytes.length; i += CHUNK_SIZE) {
+    const chunk = bytes.subarray(i, i + CHUNK_SIZE);
+    binaryString += String.fromCharCode.apply(null, chunk as unknown as number[]);
+  }
+  return btoa(binaryString);
+}
+
+export function fromBase64(base64: string): ArrayBuffer {
+  if (hasFromBase64(Uint8Array)) {
+    return Uint8Array.fromBase64(base64).buffer as ArrayBuffer;
+  }
+
+  const binary = atob(base64);
+  const bytes = Uint8Array.from(binary, (c) => c.charCodeAt(0));
+  return bytes.buffer as ArrayBuffer;
+}
diff --git a/packages/core/test/bundling/hydration/bundle.golden_symbols.json b/packages/core/test/bundling/hydration/bundle.golden_symbols.json
@@ -531,6 +531,7 @@
       "hasApplyArgsData",
       "hasAuthHeaders",
       "hasDeps",
+      "hasFromBase64",
       "hasInSkipHydrationBlockFlag",
       "hasLift",
       "hasMatchingDehydratedView",
