fix: rerun load functions when the number of values of a tracked search parameter changes

.changeset/olive-buses-shake.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: rerun load functions when the number of values of a tracked search parameter changes

packages/kit/src/runtime/client/client.js

@@ -1167,12 +1167,12 @@ function diff_search_params(old_url, new_url) {
 	const changed = new Set([...old_url.searchParams.keys(), ...new_url.searchParams.keys()]);
 
 	for (const key of changed) {
-		const old_values = old_url.searchParams.getAll(key);
-		const new_values = new_url.searchParams.getAll(key);
+		const old_values = old_url.searchParams.getAll(key).sort();
+		const new_values = new_url.searchParams.getAll(key).sort();
 
 		if (
-			old_values.every((value) => new_values.includes(value)) &&
-			new_values.every((value) => old_values.includes(value))
+			old_values.length === new_values.length &&
+			old_values.every((value, i) => value === new_values[i])
 		) {
 			changed.delete(key);
 		}

packages/kit/test/apps/basics/src/routes/load/invalidation/search-params/universal/+page.svelte

@@ -6,3 +6,4 @@
 
 <a data-id="tracked" href="?a={data.count + 1}">Change tracked parameter</a>
 <a data-id="untracked" href="?a={data.count}&b={data.count + 1}">Change untracked parameter</a>
+<a data-id="duplicate" href="?a={data.count}&a={data.count}">Duplicate tracked parameter</a>

packages/kit/test/apps/basics/test/client.test.js

@@ -525,6 +525,16 @@
 		expect(await page.textContent('span')).toBe('count: 1');
 	});
 
+	test('load function re-runs when the number of values of a tracked searchParam changes', async ({
+		page,
+		clicknav
+	}) => {
+		await page.goto('/load/invalidation/search-params/universal?a=0');
+		expect(await page.textContent('span')).toBe('count: 0');
+		await clicknav('[data-id="duplicate"]');
+		expect(await page.textContent('span')).toBe('count: 1');
+	});
+
 	test('server-only load functions are re-run following forced invalidation', async ({
 		page,
 		request,
@@ -660,7 +670,7 @@
 		expect(await page.textContent('p.shared')).toBe(next_shared);
 	});
 
 	test('+page(.server).js is re-run when server dep is invalidated following goto', async ({
 		page
 	}) => {
 		await page.goto('/load/invalidation/depends-goto');
@@ -781,7 +791,7 @@
 		expect(await page.textContent('h1')).toBe('route.id: /load/invalidation/route/shared/b');
 	});
 
 	test('route.id does not rerun layout if unchanged', async ({ page, clicknav }) => {
 		await page.goto('/load/invalidation/route/shared/unchanged-x');
 		expect(await page.textContent('h1')).toBe('route.id: /load/invalidation/route/shared/[x]');
 		const id = await page.textContent('h2');