From 15bf95f407da9c6f7db8a2589c8ec6a8608bd8b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Ahlert?= <andre@aex.partners>
Date: Thu, 30 Apr 2026 11:15:00 -0300
Subject: [PATCH] fix: anchor fetchThrowsOn regexes to avoid false positives on
 2xx/3xx

The default `fetchThrowsOn` patterns `/4.*/` and `/5.*/` are unanchored,
so any status code containing the digit 4 or 5 matches and throws.
This incorrectly fails 204, 304, 250-259, etc.

Anchor to `/^4/` and `/^5/` so only 4xx and 5xx throw, matching the
documented behavior ("fetch throws on non-2xx responses").

Fixes #670
---
 src/core/config.js     |  2 +-
 test/commands/fetch.js | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/core/config.js b/src/core/config.js
index 7c3c11299..ab596a47b 100644
--- a/src/core/config.js
+++ b/src/core/config.js
@@ -4,7 +4,7 @@ export const config = {
     attributes: "_, script, data-script",
     defaultTransition: "all 500ms ease-in",
     disableSelector: "[disable-scripting], [data-disable-scripting]",
-    fetchThrowsOn: [/4.*/, /5.*/],
+    fetchThrowsOn: [/^4/, /^5/],
     hideShowStrategies: {},
     logAll: false,
     mutatingMethods: {
diff --git a/test/commands/fetch.js b/test/commands/fetch.js
index 965ada56d..c1a5d47d2 100644
--- a/test/commands/fetch.js
+++ b/test/commands/fetch.js
@@ -196,6 +196,24 @@ test.describe("the fetch command", () => {
 		await expect(find('div')).toHaveText("the body");
 	});
 
+	test("does not throw on 204 No Content", async ({html, find, page}) => {
+		await page.route('**/test', async (route) => {
+			await route.fulfill({ status: 204, body: '' });
+		});
+		await html("<div _='on click fetch /test then put \"ok\" into me'></div>");
+		await find('div').dispatchEvent('click');
+		await expect(find('div')).toHaveText("ok");
+	});
+
+	test("does not throw on 304 Not Modified", async ({html, find, page}) => {
+		await page.route('**/test', async (route) => {
+			await route.fulfill({ status: 304, body: '' });
+		});
+		await html("<div _='on click fetch /test then put \"ok\" into me'></div>");
+		await find('div').dispatchEvent('click');
+		await expect(find('div')).toHaveText("ok");
+	});
+
 	test("as response does not throw on 404", async ({html, find, page}) => {
 		await page.route('**/test', async (route) => {
 			await route.fulfill({ status: 404, body: 'not found' });