[fix] browser only redirect during load (#2462)

.changeset/sharp-moles-hammer.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix browser-only redirect during load.

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

@@ -411,9 +411,11 @@ export class Renderer {
 	 */
 	async _get_navigation_result_from_branch({ page, branch }) {
 		const filtered = /** @type {import('./types').BranchNode[] } */ (branch.filter(Boolean));
+		const redirect = filtered.find((f) => f.loaded && f.loaded.redirect);
 
 		/** @type {import('./types').NavigationResult} */
 		const result = {
+			redirect: redirect && redirect.loaded ? redirect.loaded.redirect : undefined,
 			state: {
 				page,
 				branch,

packages/kit/test/apps/basics/src/routes/redirect-on-load/_tests.js

@@ -0,0 +1,13 @@
+import * as assert from 'uvu/assert';
+
+/** @type {import('test').TestMaker} */
+export default function (test) {
+	test('redirect-on-load', '/redirect-on-load', async ({ base, page, js }) => {
+		if (js) {
+			assert.equal(page.url(), `${base}/redirect-on-load/redirected`);
+			assert.equal(await page.textContent('h1'), 'Hazaa!');
+		} else {
+			assert.equal(page.url(), `${base}/redirect-on-load`);
+		}
+	});
+}

packages/kit/test/apps/basics/src/routes/redirect-on-load/index.svelte

@@ -0,0 +1,17 @@
+<script context="module">
+	import { browser } from '$app/env';
+
+	export async function load() {
+		if (browser) {
+			return {
+				status: 303,
+				redirect: '/redirect-on-load/redirected'
+			};
+		}
+
+		return {};
+	}
+</script>
+
+<h1>Woops!</h1>
+<p>You shouldn't be here. You should have been directed to /redirect!</p>

packages/kit/test/apps/basics/src/routes/redirect-on-load/redirected.svelte

@@ -0,0 +1 @@
+<h1>Hazaa!</h1>

packages/kit/test/test.js

@@ -197,7 +197,18 @@ function duplicate(test_fn, config, is_build) {
 
 				if (start) {
 					response = await context.pages.js.goto(context.base + start);
-					await context.pages.js.evaluate(() => window.started);
+					// Evaluate will throw an exception if the page is navigated away from while the
+					// script is executing, which may happen during redirect tests. In that case, the
+					// start event will be fired after the redirect
+					for (let i = 0; i <= 9; i++) {
+						try {
+							await context.pages.js.evaluate(() => window.started);
+							break;
+						} catch (e) {
+							if (i === 9) throw e;
+							await context.pages.js.waitForNavigation();
+						}
+					}
 				}
 
 				await callback({