From 0b0fec285d7df8675c8f5ecc42519f3734d70f72 Mon Sep 17 00:00:00 2001
From: Steven Lambert <2433219+straker@users.noreply.github.com>
Date: Fri, 8 Jan 2021 09:48:17 -0700
Subject: [PATCH] fix(color-contrast-matches): do not pass empty string to
 getElementById (#2739)

---
 lib/rules/color-contrast-matches.js | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/lib/rules/color-contrast-matches.js b/lib/rules/color-contrast-matches.js
index c3d922241b..f6f12ec47d 100644
--- a/lib/rules/color-contrast-matches.js
+++ b/lib/rules/color-contrast-matches.js
@@ -69,14 +69,17 @@ function colorContrastMatches(node, virtualNode) {
       : virtualNode;
 
     // explicit label of disabled control
-    const doc = getRootNode(labelNode);
-    const explicitControl = doc.getElementById(labelNode.htmlFor || '');
-    const explicitControlVirtual =
-      explicitControl && getNodeFromTree(explicitControl);
+    if (labelNode.htmlFor) {
+      const doc = getRootNode(labelNode);
+      const explicitControl = doc.getElementById(labelNode.htmlFor);
+      const explicitControlVirtual =
+        explicitControl && getNodeFromTree(explicitControl);
 
-    if (explicitControlVirtual && isDisabled(explicitControlVirtual)) {
-      return false;
+      if (explicitControlVirtual && isDisabled(explicitControlVirtual)) {
+        return false;
+      }
     }
+
     // implicit label of disabled control
     const query =
       'input:not([type="hidden"]):not([type="image"])' +