add check to @aws-amplify/backend to throw early in a browser conte…

…xt (#1810)

* add check to secret() to throw early in a browser context

* "client-side applications" -> "the browser"

* lift "is browser" check to a utility, execute at package entrypoint

* remove stale check from secret()

* update changeset description

* Update packages/backend/src/is_browser.ts

Co-authored-by: Kamil Sobol <[email protected]>

---------

Co-authored-by: Kamil Sobol <[email protected]>

.changeset/friendly-cameras-trade.md

@@ -0,0 +1,5 @@
+---
+'@aws-amplify/backend': patch
+---
+
+add check to `@aws-amplify/backend` entrypoint to throw early in a browser context

packages/backend/src/index.ts

@@ -1,3 +1,11 @@
+import { isBrowser } from './is_browser.js';
+
+if (isBrowser()) {
+  throw new Error(
+    'This package is for backend use only and should not be used in a browser environment.'
+  );
+}
+
 export { defineBackend } from './backend_factory.js';
 export * from './backend.js';
 export * from './secret.js';

packages/backend/src/is_browser.test.ts

@@ -0,0 +1,25 @@
+import { equal } from 'node:assert/strict';
+import { afterEach, describe, it } from 'node:test';
+import { isBrowser } from './is_browser.js';
+
+void describe('is browser', () => {
+  void afterEach(() => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    delete (global as any).window;
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    delete (global as any).document;
+  });
+
+  void it('should be true in a browser context', () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (global as any).window = {};
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (global as any).document = {};
+
+    equal(isBrowser(), true);
+  });
+
+  void it('should be false in a node context', () => {
+    equal(isBrowser(), false);
+  });
+});

packages/backend/src/is_browser.ts

@@ -0,0 +1,7 @@
+/**
+ * Checks whether we are in a browser
+ */
+export const isBrowser = () => {
+  // @ts-expect-error we're checking for browser context and globalThis does not have an index signature
+  return typeof globalThis.window !== 'undefined';
+};