From b950a64406a55063f4e99905f34ff7fdc7ccef2c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Greg=20Berg=C3=A9?= <berge.greg@gmail.com>
Date: Wed, 8 Jan 2025 11:08:29 +0100
Subject: [PATCH] improve browser support (#2693)

---
 .changeset/stupid-beans-travel.md                        | 5 +++++
 packages/gitbook/src/components/Ads/Ad.tsx               | 4 ++++
 .../gitbook/src/components/hooks/useScrollActiveId.ts    | 4 ++++
 packages/gitbook/src/components/utils/ZoomImage.tsx      | 9 +++++++--
 4 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/stupid-beans-travel.md

diff --git a/.changeset/stupid-beans-travel.md b/.changeset/stupid-beans-travel.md
new file mode 100644
index 000000000..b622042b4
--- /dev/null
+++ b/.changeset/stupid-beans-travel.md
@@ -0,0 +1,5 @@
+---
+'gitbook': patch
+---
+
+Avoid errors on legacy browsers
diff --git a/packages/gitbook/src/components/Ads/Ad.tsx b/packages/gitbook/src/components/Ads/Ad.tsx
index 2273baf59..4a15b862d 100644
--- a/packages/gitbook/src/components/Ads/Ad.tsx
+++ b/packages/gitbook/src/components/Ads/Ad.tsx
@@ -44,6 +44,10 @@ export function Ad({
             return;
         }
 
+        if (typeof IntersectionObserver === 'undefined') {
+            return;
+        }
+
         const observer = new IntersectionObserver(
             ([entry]) => {
                 if (entry.isIntersecting) {
diff --git a/packages/gitbook/src/components/hooks/useScrollActiveId.ts b/packages/gitbook/src/components/hooks/useScrollActiveId.ts
index 6ffe9a7c8..fa3f9ddda 100644
--- a/packages/gitbook/src/components/hooks/useScrollActiveId.ts
+++ b/packages/gitbook/src/components/hooks/useScrollActiveId.ts
@@ -18,6 +18,10 @@ export function useScrollActiveId(
     React.useEffect(() => {
         setActiveId(null);
 
+        if (typeof IntersectionObserver === 'undefined') {
+            return;
+        }
+
         const onObserve: IntersectionObserverCallback = (entries) => {
             /**
              * We need to keep track of all the sections that are intersecting
diff --git a/packages/gitbook/src/components/utils/ZoomImage.tsx b/packages/gitbook/src/components/utils/ZoomImage.tsx
index 1fcddacad..77f52645a 100644
--- a/packages/gitbook/src/components/utils/ZoomImage.tsx
+++ b/packages/gitbook/src/components/utils/ZoomImage.tsx
@@ -63,7 +63,10 @@ export function ZoomImage(
             }
         };
 
-        mediaQueryList.addEventListener('change', onChange);
+        if ('addEventListener' in mediaQueryList) {
+            mediaQueryList.addEventListener('change', onChange);
+        }
+
         if (imgRef.current) {
             resizeObserver?.observe(imgRef.current);
         }
@@ -75,7 +78,9 @@ export function ZoomImage(
 
         return () => {
             resizeObserver?.disconnect();
-            mediaQueryList.removeEventListener('change', onChange);
+            if ('removeEventListener' in mediaQueryList) {
+                mediaQueryList.removeEventListener('change', onChange);
+            }
         };
     }, [imgRef, width]);