From 923cb1da58cf148dc444509b12e58e26ffe22646 Mon Sep 17 00:00:00 2001
From: Ferit <frtcm11@gmail.com>
Date: Sat, 10 Oct 2026 21:07:44 +0300
Subject: [PATCH] fix: observe fallbackInView option updates in InView

---
 .../src/InView.tsx                            |  3 ++-
 .../src/__tests__/InView.test.tsx             | 24 +++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/packages/react-intersection-observer/src/InView.tsx b/packages/react-intersection-observer/src/InView.tsx
index ab159dc5..ca60d28b 100644
--- a/packages/react-intersection-observer/src/InView.tsx
+++ b/packages/react-intersection-observer/src/InView.tsx
@@ -94,7 +94,8 @@ export class InView extends React.Component<
       prevProps.triggerOnce !== this.props.triggerOnce ||
       prevProps.skip !== this.props.skip ||
       prevProps.trackVisibility !== this.props.trackVisibility ||
-      prevProps.delay !== this.props.delay
+      prevProps.delay !== this.props.delay ||
+      prevProps.fallbackInView !== this.props.fallbackInView
     ) {
       this.unobserve();
       this.observeNode();
diff --git a/packages/react-intersection-observer/src/__tests__/InView.test.tsx b/packages/react-intersection-observer/src/__tests__/InView.test.tsx
index 971e9d0c..ede3976d 100644
--- a/packages/react-intersection-observer/src/__tests__/InView.test.tsx
+++ b/packages/react-intersection-observer/src/__tests__/InView.test.tsx
@@ -301,6 +301,30 @@ test("should render with fallback", () => {
   }).toThrow();
 });
 
+test("should update fallbackInView when the observer is unsupported", () => {
+  // @ts-expect-error Simulate a browser without IntersectionObserver.
+  window.IntersectionObserver = undefined;
+  const callback = vi.fn();
+  const { rerender } = render(
+    <InView fallbackInView={true} onChange={callback}>
+      {({ inView, ref }) => <div ref={ref}>{inView.toString()}</div>}
+    </InView>,
+  );
+  screen.getByText("true");
+
+  rerender(
+    <InView fallbackInView={false} onChange={callback}>
+      {({ inView, ref }) => <div ref={ref}>{inView.toString()}</div>}
+    </InView>,
+  );
+
+  screen.getByText("false");
+  expect(callback).toHaveBeenLastCalledWith(
+    false,
+    expect.objectContaining({ isIntersecting: false }),
+  );
+});
+
 test("should render with global fallback", () => {
   const cb = vi.fn();
   // @ts-expect-error