diff --git a/Tests/LibWeb/Text/expected/text-insertData.txt b/Tests/LibWeb/Text/expected/text-insertData.txt
new file mode 100644
index 00000000000..241c76b933b
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/text-insertData.txt
@@ -0,0 +1 @@
+=Привет=
diff --git a/Tests/LibWeb/Text/input/text-insertData.html b/Tests/LibWeb/Text/input/text-insertData.html
new file mode 100644
index 00000000000..ed65954c480
--- /dev/null
+++ b/Tests/LibWeb/Text/input/text-insertData.html
@@ -0,0 +1,13 @@
+
+
+==
+
diff --git a/Userland/Libraries/LibWeb/DOM/CharacterData.cpp b/Userland/Libraries/LibWeb/DOM/CharacterData.cpp
index 42d9cb64b75..7dd4c71e02a 100644
--- a/Userland/Libraries/LibWeb/DOM/CharacterData.cpp
+++ b/Userland/Libraries/LibWeb/DOM/CharacterData.cpp
@@ -72,6 +72,8 @@ WebIDL::ExceptionOr CharacterData::replace_data(size_t offset, size_t coun
Utf16View utf16_view { utf16_data };
auto length = utf16_view.length_in_code_units();
+ auto inserted_data_length_in_utf16_code_units = AK::utf16_code_unit_length_from_utf8(data);
+
// 2. If offset is greater than length, then throw an "IndexSizeError" DOMException.
if (offset > length)
return WebIDL::IndexSizeError::create(realm(), "Replacement offset out of range."_string);
@@ -107,14 +109,14 @@ WebIDL::ExceptionOr CharacterData::replace_data(size_t offset, size_t coun
// 10. For each live range whose start node is node and start offset is greater than offset plus count, increase its start offset by data’s length and decrease it by count.
for (auto& range : Range::live_ranges()) {
if (range->start_container() == this && range->start_offset() > (offset + count))
- TRY(range->set_start(*range->start_container(), range->start_offset() + data.bytes().size() - count));
+ TRY(range->set_start(*range->start_container(), range->start_offset() + inserted_data_length_in_utf16_code_units - count));
}
// 11. For each live range whose end node is node and end offset is greater than offset plus count, increase its end offset by data’s length and decrease it by count.
for (auto& range : Range::live_ranges()) {
if (range->end_container() == this && range->end_offset() > (offset + count)) {
// AD-HOC: Clamp offset to the end of the data if it's too large.
- auto new_offset = min(range->end_offset() + data.bytes().size() - count, m_data.bytes().size());
+ auto new_offset = min(range->end_offset() + inserted_data_length_in_utf16_code_units - count, length_in_utf16_code_units());
TRY(range->set_end(*range->end_container(), new_offset));
}
}