From 12acf7e4a02053e91133c8b569ca312d8fb87478 Mon Sep 17 00:00:00 2001
From: doodlewind <7312949+doodlewind@users.noreply.github.com>
Date: Fri, 28 Feb 2025 11:50:56 +0000
Subject: [PATCH] fix(editor): range IndexSizeError on firefox (#10519)

This is a Firefox compat issue, I've manually confirmed this implementation works in latest Firefox build.
---
 .../affine/shared/src/utils/dom/point-to-range.ts     | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/blocksuite/affine/shared/src/utils/dom/point-to-range.ts b/blocksuite/affine/shared/src/utils/dom/point-to-range.ts
index 9d842f8159..d7e879c844 100644
--- a/blocksuite/affine/shared/src/utils/dom/point-to-range.ts
+++ b/blocksuite/affine/shared/src/utils/dom/point-to-range.ts
@@ -28,7 +28,16 @@ export function caretRangeFromPoint(
     }
     // TODO handle caret is covered by popup
     const range = document.createRange();
-    range.setStart(caret.offsetNode, caret.offset);
+    let offset = caret.offset;
+    if (caret.offsetNode.nodeType === Node.TEXT_NODE) {
+      const textNode = caret.offsetNode as Text;
+      offset = Math.max(0, Math.min(offset, textNode.length));
+    } else if (caret.offsetNode.nodeType === Node.ELEMENT_NODE) {
+      const elementNode = caret.offsetNode as Element;
+      offset = Math.max(0, Math.min(offset, elementNode.childNodes.length));
+    }
+
+    range.setStart(caret.offsetNode, offset);
     return range;
   }