From 4a4602137b5448a9e5fce8f09d079fd8b0f0f688 Mon Sep 17 00:00:00 2001
From: Pierre Tachoire <pierre@lightpanda.io>
Date: Tue, 25 Nov 2025 11:46:54 +0100
Subject: [PATCH 1/2] element: add prefix and localName accessors

---
 .../tests/document/create_element_ns.html     |  8 ++++++++
 src/browser/webapi/Element.zig                | 20 +++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/browser/tests/document/create_element_ns.html b/src/browser/tests/document/create_element_ns.html
index c14a2773..5a75c359 100644
--- a/src/browser/tests/document/create_element_ns.html
+++ b/src/browser/tests/document/create_element_ns.html
@@ -28,5 +28,13 @@
 
   const regularDiv = document.createElement('div');
   testing.expectEqual('DIV', regularDiv.tagName);
+  testing.expectEqual('div', regularDiv.localName);
+  testing.expectEqual(null, regularDiv.prefix);
   testing.expectEqual('http://www.w3.org/1999/xhtml', regularDiv.namespaceURI);
+
+  const custom = document.createElementNS('test', 'te:ST');
+  testing.expectEqual('TE:ST', custom.tagName); // Should be te:ST
+  testing.expectEqual('te', custom.prefix);
+  testing.expectEqual('ST', custom.localName);
+  testing.expectEqual('http://www.w3.org/1999/xhtml', custom.namespaceURI); // Should be test
 </script>
diff --git a/src/browser/webapi/Element.zig b/src/browser/webapi/Element.zig
index 023da510..81427e0b 100644
--- a/src/browser/webapi/Element.zig
+++ b/src/browser/webapi/Element.zig
@@ -913,6 +913,26 @@ pub const JsApi = struct {
         return buf.written();
     }
 
+    pub const prefix = bridge.accessor(_prefix, null, .{});
+    fn _prefix(self: *Element) ?[]const u8 {
+        const name = self.getTagNameLower();
+        if (std.mem.indexOfPos(u8, name, 0, ":")) |pos| {
+            return name[0..pos];
+        }
+
+        return null;
+    }
+
+    pub const localName = bridge.accessor(_localName, null, .{});
+    fn _localName(self: *Element) []const u8 {
+        const name = self.getTagNameLower();
+        if (std.mem.indexOfPos(u8, name, 0, ":")) |pos| {
+            return name[pos + 1 ..];
+        }
+
+        return name;
+    }
+
     pub const id = bridge.accessor(Element.getId, Element.setId, .{});
     pub const className = bridge.accessor(Element.getClassName, Element.setClassName, .{});
     pub const classList = bridge.accessor(Element.getClassList, null, .{});

From a0fa232a3a3852bc163fbbce081784644b36aaef Mon Sep 17 00:00:00 2001
From: Pierre Tachoire <pierre@lightpanda.io>
Date: Tue, 25 Nov 2025 12:12:00 +0100
Subject: [PATCH 2/2] element: upper case only the suffix part of the tagname

---
 src/browser/tests/document/create_element_ns.html |  2 +-
 src/browser/webapi/Element.zig                    | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/browser/tests/document/create_element_ns.html b/src/browser/tests/document/create_element_ns.html
index 5a75c359..46773ebc 100644
--- a/src/browser/tests/document/create_element_ns.html
+++ b/src/browser/tests/document/create_element_ns.html
@@ -33,7 +33,7 @@
   testing.expectEqual('http://www.w3.org/1999/xhtml', regularDiv.namespaceURI);
 
   const custom = document.createElementNS('test', 'te:ST');
-  testing.expectEqual('TE:ST', custom.tagName); // Should be te:ST
+  testing.expectEqual('te:ST', custom.tagName);
   testing.expectEqual('te', custom.prefix);
   testing.expectEqual('ST', custom.localName);
   testing.expectEqual('http://www.w3.org/1999/xhtml', custom.namespaceURI); // Should be test
diff --git a/src/browser/webapi/Element.zig b/src/browser/webapi/Element.zig
index 81427e0b..c1608425 100644
--- a/src/browser/webapi/Element.zig
+++ b/src/browser/webapi/Element.zig
@@ -767,7 +767,15 @@ fn upperTagName(tag_name: *String, buf: []u8) []const u8 {
         log.info(.dom, "tag.long.name", .{ .name = tag_name.str() });
         return tag_name.str();
     }
-    return std.ascii.upperString(buf, tag_name.str());
+    const tag = tag_name.str();
+    // If the tag_name has a prefix, we must uppercase only the suffix part.
+    // example: te:st should be returned as te:ST.
+    if (std.mem.indexOfPos(u8, tag, 0, ":")) |pos| {
+        @memcpy(buf[0 .. pos + 1], tag[0 .. pos + 1]);
+        _ = std.ascii.upperString(buf[pos..tag.len], tag[pos..tag.len]);
+        return buf[0..tag.len];
+    }
+    return std.ascii.upperString(buf, tag);
 }
 
 pub fn getTag(self: *const Element) Tag {