From 3514c77f7230dc0cbf5c3e220ef23827a0d4f0e7 Mon Sep 17 00:00:00 2001
From: Steven Lambert <2433219+straker@users.noreply.github.com>
Date: Thu, 11 Jun 2026 09:29:28 -0600
Subject: [PATCH] fix(gather-internals): handle non-HTMLElement nodes

---
 eslint.config.js                  | 14 ++++++++++++++
 lib/gather-internals/walk-tree.js |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/eslint.config.js b/eslint.config.js
index 091ce2f0c9..294c01de53 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -84,6 +84,20 @@ module.exports = [
             'CallExpression[callee.object.property.name=actualNode][callee.property.name=contains]',
           message:
             "Don't use node.contains(node2) as it doesn't work across shadow DOM. Use axe.utils.contains(node, node2) instead."
+        },
+        {
+          // window.HTMLElement
+          selector:
+            'MemberExpression[object.name=window][property.name=HTMLElement]',
+          message:
+            "Don't use window.HTMLElement as it doesn't include all DOM node types, such as SVGs. Use window.Node instead."
+        },
+        {
+          // globalThis.HTMLElement
+          selector:
+            'MemberExpression[object.name=globalThis][property.name=HTMLElement]',
+          message:
+            "Don't use globalThis.HTMLElement as it doesn't include all DOM node types, such as SVGs. Use globalThis.Node instead."
         }
       ]
     },
diff --git a/lib/gather-internals/walk-tree.js b/lib/gather-internals/walk-tree.js
index c1cf0fe125..5f562a1b77 100644
--- a/lib/gather-internals/walk-tree.js
+++ b/lib/gather-internals/walk-tree.js
@@ -37,7 +37,7 @@ export function walkTree(tree = document.body) {
 
           // convert idref to node ancestry
           // aria props can use unattached nodes but those won't be used by the browser to calculate the prop value
-          if (value instanceof globalThis.HTMLElement) {
+          if (value instanceof globalThis.Node) {
             internals[prop] = value.isConnected
               ? { type: 'HTMLElement', value: getAncestry(value) }
               : undefined;