From 9a0eec3be43a9e4d7a63fcd41314d17700cc7c84 Mon Sep 17 00:00:00 2001
From: Jalil Arfaoui <jalil@arfaoui.net>
Date: Fri, 23 Jan 2026 01:09:55 +0100
Subject: [PATCH] fix: [#2034] QuerySelector fails to match attribute values
 containing quotes

When using querySelector with an attribute selector, values containing
apostrophes in double-quoted selectors (or double quotes in single-quoted
selectors) were not matched correctly.

For example, [data-value="it's a test"] would fail to find elements
with that attribute value.

The issue was in the regex that captures attribute values: it excluded
both quote types regardless of which delimiter was used.

The fix uses lookbehind/lookahead assertions to correctly match the
value based on the actual delimiter used.
---
 .../src/query-selector/SelectorParser.ts       |  2 +-
 .../test/query-selector/QuerySelector.test.ts  | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/packages/happy-dom/src/query-selector/SelectorParser.ts b/packages/happy-dom/src/query-selector/SelectorParser.ts
index 95c3e3e73..7c490d44b 100644
--- a/packages/happy-dom/src/query-selector/SelectorParser.ts
+++ b/packages/happy-dom/src/query-selector/SelectorParser.ts
@@ -27,7 +27,7 @@ import DocumentFragment from '../nodes/document-fragment/DocumentFragment.js';
  * Group 17: Combinator.
  */
 const SELECTOR_REGEXP =
-	/(\*)|([a-zA-Z0-9-]+)|#((?:[a-zA-Z0-9-_«»]|\\.)+)|\.((?:[a-zA-Z0-9-_«»]|\\.)+)|\[([a-zA-Z0-9-_\\:]+)\]|\[([a-zA-Z0-9-_\\:]+)\s*([~|^$*]{0,1})\s*=\s*["']{1}([^"']*)["']{1}\s*(s|i){0,1}\]|\[([a-zA-Z0-9-_]+)\s*([~|^$*]{0,1})\s*=\s*([^\]]*)\]|:([a-zA-Z-]+)\s*\(((?:[^()]|\[[^\]]*\]|\([^()]*\))*)\){0,1}|:([a-zA-Z-]+)|::([a-zA-Z-]+)|([\s,+>~]*)/gm;
+	/(\*)|([a-zA-Z0-9-]+)|#((?:[a-zA-Z0-9-_«»]|\\.)+)|\.((?:[a-zA-Z0-9-_«»]|\\.)+)|\[([a-zA-Z0-9-_\\:]+)\]|\[([a-zA-Z0-9-_\\:]+)\s*([~|^$*]{0,1})\s*=\s*["']((?<=")[^"]*(?=")|(?<=')[^']*(?='))["']\s*(s|i){0,1}\]|\[([a-zA-Z0-9-_]+)\s*([~|^$*]{0,1})\s*=\s*([^\]]*)\]|:([a-zA-Z-]+)\s*\(((?:[^()]|\[[^\]]*\]|\([^()]*\))*)\){0,1}|:([a-zA-Z-]+)|::([a-zA-Z-]+)|([\s,+>~]*)/gm;
 
 /**
  * Escaped Character RegExp.
diff --git a/packages/happy-dom/test/query-selector/QuerySelector.test.ts b/packages/happy-dom/test/query-selector/QuerySelector.test.ts
index 05be773cf..b8b87b1a4 100644
--- a/packages/happy-dom/test/query-selector/QuerySelector.test.ts
+++ b/packages/happy-dom/test/query-selector/QuerySelector.test.ts
@@ -502,6 +502,24 @@ describe('QuerySelector', () => {
 			expect(elements[1] === container.children[0].children[1].children[1]).toBe(true);
 		});
 
+		it('Returns elements with attribute values containing apostrophes using double quotes as delimiter.', () => {
+			const container = document.createElement('div');
+			container.innerHTML = `<div data-value="it's a test">Content</div>`;
+
+			const elements = container.querySelectorAll('[data-value="it\'s a test"]');
+			expect(elements.length).toBe(1);
+			expect(elements[0] === container.children[0]).toBe(true);
+		});
+
+		it('Returns elements with attribute values containing double quotes using apostrophes as delimiter.', () => {
+			const container = document.createElement('div');
+			container.innerHTML = `<div data-value='say "hello"'>Content</div>`;
+
+			const elements = container.querySelectorAll('[data-value=\'say "hello"\']');
+			expect(elements.length).toBe(1);
+			expect(elements[0] === container.children[0]).toBe(true);
+		});
+
 		it('Returns all elements with tag name and matching attributes using "span[_attr1]".', () => {
 			const container = document.createElement('div');
 			container.innerHTML = QuerySelectorHTML.replace(/ attr1/gm, '_attr1');