From 571f73171e62144fcf19a883f6e4ef631b827694 Mon Sep 17 00:00:00 2001
From: Tee Ming <chewteeming01@gmail.com>
Date: Wed, 9 Oct 2024 18:15:14 +0800
Subject: [PATCH] fix: only preload link if the URL differs from current page
 (#12773)

fixes #10234

By avoiding preloading pages where the URL pathname and search params (the load ID) are unchanged, we also avoid mistakenly caching navigation results for hash URLs. Currently, these are ID'd the same as URLs without hashes, causing navigation to lose track of the current URL (hence the original issue).

This should be a good solution because:

- if we're on already on the page we don't need new load results for it.
- even if the load results are suppose to be different for the same URL, clicking on a link that leads to the exact same URL already does nothing.
---
 .changeset/calm-fireants-hug.md                     |  5 +++++
 packages/kit/src/runtime/client/client.js           |  5 ++++-
 .../basics/src/routes/routing/hashes/a/+page.svelte |  3 +++
 .../apps/basics/test/cross-platform/client.test.js  | 13 +++++++++++++
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/calm-fireants-hug.md

diff --git a/.changeset/calm-fireants-hug.md b/.changeset/calm-fireants-hug.md
new file mode 100644
index 000000000000..b4ade6d2f778
--- /dev/null
+++ b/.changeset/calm-fireants-hug.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: only preload links that have a different URL than the current page
diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index cd5288dbb0d4..715ef84cff9e 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -1543,7 +1543,10 @@ function setup_preload() {
 
 		const options = get_router_options(a);
 
-		if (!options.reload) {
+		// we don't want to preload data for a page we're already on
+		const same_url = url && current.url.pathname + current.url.search === url.pathname + url.search;
+
+		if (!options.reload && !same_url) {
 			if (priority <= options.preload_data) {
 				const intent = get_navigation_intent(url, false);
 				if (intent) {
diff --git a/packages/kit/test/apps/basics/src/routes/routing/hashes/a/+page.svelte b/packages/kit/test/apps/basics/src/routes/routing/hashes/a/+page.svelte
index 7ac5f9c2a32b..7715b3d2458d 100644
--- a/packages/kit/test/apps/basics/src/routes/routing/hashes/a/+page.svelte
+++ b/packages/kit/test/apps/basics/src/routes/routing/hashes/a/+page.svelte
@@ -2,3 +2,6 @@
 <a href="#hash-target">hash link</a>
 <a href="/routing/hashes/b">b</a>
 <a href="#replace-state" data-sveltekit-replacestate>replace state</a>
+
+<a data-sveltekit-preload-data href="/routing/hashes/a">/routing/hashes/a</a>
+<a data-sveltekit-preload-data href="#preload">#preload</a>
diff --git a/packages/kit/test/apps/basics/test/cross-platform/client.test.js b/packages/kit/test/apps/basics/test/cross-platform/client.test.js
index b8f485fc228d..7f57086b4048 100644
--- a/packages/kit/test/apps/basics/test/cross-platform/client.test.js
+++ b/packages/kit/test/apps/basics/test/cross-platform/client.test.js
@@ -615,6 +615,19 @@ test.describe('Prefetching', () => {
 		await expect(page.locator('h1')).not.toHaveText('Oopsie');
 	});
 
+	test('same route hash links work more than once', async ({ page, clicknav, baseURL }) => {
+		await page.goto('/routing/hashes/a');
+
+		await clicknav('[href="#preload"]');
+		await expect(page.url()).toBe(`${baseURL}/routing/hashes/a#preload`);
+
+		await clicknav('[href="/routing/hashes/a"]');
+		await expect(page.url()).toBe(`${baseURL}/routing/hashes/a`);
+
+		await clicknav('[href="#preload"]');
+		await expect(page.url()).toBe(`${baseURL}/routing/hashes/a#preload`);
+	});
+
 	test('does not rerun load on calls to duplicate preload hash route', async ({ app, page }) => {
 		await page.goto('/routing/a');