From 1985b5608107f9da3e05c7375d13c1631a5cfb59 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Thu, 25 Aug 2022 22:55:14 -0400
Subject: [PATCH 01/23] serialize initial data with devalue

---
 packages/kit/src/runtime/client/client.js     | 28 ++++-------
 packages/kit/src/runtime/client/start.js      |  2 +
 packages/kit/src/runtime/client/types.d.ts    |  2 +
 packages/kit/src/runtime/server/index.js      |  1 -
 packages/kit/src/runtime/server/page/index.js |  1 -
 .../kit/src/runtime/server/page/load_data.js  | 46 +------------------
 .../kit/src/runtime/server/page/render.js     |  4 +-
 .../runtime/server/page/respond_with_error.js |  1 -
 .../src/routes/load/devalue/+page.svelte      |  1 +
 .../routes/load/devalue/regex/+page.server.js |  6 +++
 .../routes/load/devalue/regex/+page.svelte    |  6 +++
 packages/kit/test/apps/basics/test/test.js    |  7 +++
 ...vite.config.js.timestamp-1661481874774.mjs | 23 ++++++++++
 13 files changed, 60 insertions(+), 68 deletions(-)
 create mode 100644 packages/kit/test/apps/basics/src/routes/load/devalue/+page.svelte
 create mode 100644 packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.server.js
 create mode 100644 packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.svelte
 create mode 100644 packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 0fa99bd6fecd..15260442d496 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -1281,31 +1281,21 @@ export function create_client({ target, base, trailing_slash }) {
 			});
 		},
 
-		_hydrate: async ({ status, error, node_ids, params, routeId }) => {
+		_hydrate: async ({
+			status,
+			error,
+			node_ids,
+			params,
+			routeId,
+			data: server_data_nodes,
+			errors: validation_errors
+		}) => {
 			const url = new URL(location.href);
 
 			/** @type {import('./types').NavigationFinished | undefined} */
 			let result;
 
 			try {
-				/**
-				 * @param {string} type
-				 * @param {any} fallback
-				 */
-				const parse = (type, fallback) => {
-					const script = document.querySelector(`script[sveltekit\\:data-type="${type}"]`);
-					return script?.textContent ? JSON.parse(script.textContent) : fallback;
-				};
-				/**
-				 * @type {Array<import('types').ServerDataNode | null>}
-				 * On initial navigation, this will only consist of data nodes or `null`.
-				 * A possible error is passed through the `error` property, in which case
-				 * the last entry of `node_ids` is an error page and the last entry of
-				 * `server_data_nodes` is `null`.
-				 */
-				const server_data_nodes = parse('server_data', []);
-				const validation_errors = parse('validation_errors', undefined);
-
 				const branch_promises = node_ids.map(async (n, i) => {
 					return load_node({
 						loader: nodes[n],
diff --git a/packages/kit/src/runtime/client/start.js b/packages/kit/src/runtime/client/start.js
index 2c679c8a6cc2..78c245841616 100644
--- a/packages/kit/src/runtime/client/start.js
+++ b/packages/kit/src/runtime/client/start.js
@@ -20,6 +20,8 @@ export { set_public_env } from '../env-public.js';
  *     node_ids: number[];
  *     params: Record<string, string>;
  *     routeId: string | null;
+ *     data: Array<import('types').ServerDataNode | import('types').ServerErrorNode | null>;
+ *     errors: Record<string, any> | null;
  *   };
  * }} opts
  */
diff --git a/packages/kit/src/runtime/client/types.d.ts b/packages/kit/src/runtime/client/types.d.ts
index 1b32c231ca28..bc470bf60eee 100644
--- a/packages/kit/src/runtime/client/types.d.ts
+++ b/packages/kit/src/runtime/client/types.d.ts
@@ -27,6 +27,8 @@ export interface Client {
 		node_ids: number[];
 		params: Record<string, string>;
 		routeId: string | null;
+		data: Array<import('types').ServerDataNode | import('types').ServerErrorNode | null>;
+		errors: Record<string, any>;
 	}) => Promise<void>;
 	_start_router: () => void;
 }
diff --git a/packages/kit/src/runtime/server/index.js b/packages/kit/src/runtime/server/index.js
index ee8fe42a27fb..f1f2b96cce20 100644
--- a/packages/kit/src/runtime/server/index.js
+++ b/packages/kit/src/runtime/server/index.js
@@ -272,7 +272,6 @@ export async function respond(request, options, state) {
 										// == because it could be undefined (in dev) or null (in build, because of JSON.stringify)
 										const node = n == undefined ? n : await options.manifest._.nodes[n]();
 										return load_server_data({
-											dev: options.dev,
 											event,
 											state,
 											node,
diff --git a/packages/kit/src/runtime/server/page/index.js b/packages/kit/src/runtime/server/page/index.js
index 99911ae83897..838fe9342aba 100644
--- a/packages/kit/src/runtime/server/page/index.js
+++ b/packages/kit/src/runtime/server/page/index.js
@@ -166,7 +166,6 @@ export async function render_page(event, route, page, options, state, resolve_op
 					}
 
 					return await load_server_data({
-						dev: options.dev,
 						event,
 						state,
 						node,
diff --git a/packages/kit/src/runtime/server/page/load_data.js b/packages/kit/src/runtime/server/page/load_data.js
index 237808de5126..21a753e50b0d 100644
--- a/packages/kit/src/runtime/server/page/load_data.js
+++ b/packages/kit/src/runtime/server/page/load_data.js
@@ -3,7 +3,6 @@ import { disable_search, make_trackable } from '../../../utils/url.js';
 /**
  * Calls the user's `load` function.
  * @param {{
- *   dev: boolean;
  *   event: import('types').RequestEvent;
  *   state: import('types').SSRState;
  *   node: import('types').SSRNode | undefined;
@@ -11,7 +10,7 @@ import { disable_search, make_trackable } from '../../../utils/url.js';
  * }} opts
  * @returns {Promise<import('types').ServerDataNode | null>}
  */
-export async function load_server_data({ dev, event, state, node, parent }) {
+export async function load_server_data({ event, state, node, parent }) {
 	if (!node?.server) return null;
 
 	const uses = {
@@ -53,10 +52,6 @@ export async function load_server_data({ dev, event, state, node, parent }) {
 
 	const data = result ? await unwrap_promises(result) : null;
 
-	if (dev) {
-		check_serializability(data, /** @type {string} */ (node.server_id), 'data');
-	}
-
 	return {
 		type: 'data',
 		data,
@@ -127,42 +122,3 @@ async function unwrap_promises(object) {
 
 	return unwrapped;
 }
-
-/**
- * Check that the data can safely be serialized to JSON
- * @param {any} value
- * @param {string} id
- * @param {string} path
- */
-function check_serializability(value, id, path) {
-	const type = typeof value;
-
-	if (type === 'string' || type === 'boolean' || type === 'number' || type === 'undefined') {
-		// primitives are fine
-		return;
-	}
-
-	if (type === 'object') {
-		// nulls are fine...
-		if (!value) return;
-
-		// ...so are plain arrays...
-		if (Array.isArray(value)) {
-			value.forEach((child, i) => {
-				check_serializability(child, id, `${path}[${i}]`);
-			});
-			return;
-		}
-
-		// ...and objects
-		const tag = Object.prototype.toString.call(value);
-		if (tag === '[object Object]') {
-			for (const key in value) {
-				check_serializability(value[key], id, `${path}.${key}`);
-			}
-			return;
-		}
-	}
-
-	throw new Error(`${path} returned from 'load' in ${id} cannot be serialized as JSON`);
-}
diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
index d97f0f54c25b..a42e79c6fb80 100644
--- a/packages/kit/src/runtime/server/page/render.js
+++ b/packages/kit/src/runtime/server/page/render.js
@@ -191,7 +191,9 @@ export async function render_response({
 				error: ${error && serialize_error(error, e => e.stack)},
 				node_ids: [${branch.map(({ node }) => node.index).join(', ')}],
 				params: ${devalue(event.params)},
-				routeId: ${s(event.routeId)}
+				routeId: ${s(event.routeId)},
+				data: ${devalue(branch.map(({ server_data }) => server_data))},
+				errors: ${validation_errors ? devalue(validation_errors) : 'null'}
 			}` : 'null'}
 		});
 	`;
diff --git a/packages/kit/src/runtime/server/page/respond_with_error.js b/packages/kit/src/runtime/server/page/respond_with_error.js
index 001fdd5a8cea..b0f87a5f5859 100644
--- a/packages/kit/src/runtime/server/page/respond_with_error.js
+++ b/packages/kit/src/runtime/server/page/respond_with_error.js
@@ -35,7 +35,6 @@ export async function respond_with_error({ event, options, state, status, error,
 			const default_layout = await options.manifest._.nodes[0](); // 0 is always the root layout
 
 			const server_data_promise = load_server_data({
-				dev: options.dev,
 				event,
 				state,
 				node: default_layout,
diff --git a/packages/kit/test/apps/basics/src/routes/load/devalue/+page.svelte b/packages/kit/test/apps/basics/src/routes/load/devalue/+page.svelte
new file mode 100644
index 000000000000..d339ec6ff7d2
--- /dev/null
+++ b/packages/kit/test/apps/basics/src/routes/load/devalue/+page.svelte
@@ -0,0 +1 @@
+<a href="/load/devalue/regex">/load/devalue/regex</a>
diff --git a/packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.server.js b/packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.server.js
new file mode 100644
index 000000000000..a31da9c7128e
--- /dev/null
+++ b/packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.server.js
@@ -0,0 +1,6 @@
+/** @type {import('./$types').PageServerLoad} */
+export function load() {
+	return {
+		regex: /hello/
+	};
+}
diff --git a/packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.svelte b/packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.svelte
new file mode 100644
index 000000000000..04f11dbe10a3
--- /dev/null
+++ b/packages/kit/test/apps/basics/src/routes/load/devalue/regex/+page.svelte
@@ -0,0 +1,6 @@
+<script>
+	/** @type {import('./$types').PageData} */
+	export let data;
+</script>
+
+<h1>{data.regex.test('hello')}</h1>
diff --git a/packages/kit/test/apps/basics/test/test.js b/packages/kit/test/apps/basics/test/test.js
index 1cc532aaefbf..497a409a3fec 100644
--- a/packages/kit/test/apps/basics/test/test.js
+++ b/packages/kit/test/apps/basics/test/test.js
@@ -892,6 +892,13 @@ test.describe('Load', () => {
 		expect(await page.textContent('h1')).toBe('foo.bar: Custom layout');
 		expect(await page.textContent('h2')).toBe('pagedata: pagedata');
 	});
+
+	test.only('Serializes non-JSON data', async ({ page, clicknav }) => {
+		await page.goto('/load/devalue');
+		await clicknav('[href="/load/devalue/regex"]');
+
+		expect(await page.textContent('h1')).toBe(true);
+	});
 });
 
 test.describe('Method overrides', () => {
diff --git a/packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs b/packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs
new file mode 100644
index 000000000000..d0793c197a93
--- /dev/null
+++ b/packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs
@@ -0,0 +1,23 @@
+// vite.config.js
+import * as path from "path";
+import { sveltekit } from "@sveltejs/kit/vite";
+var config = {
+  build: {
+    minify: false
+  },
+  clearScreen: false,
+  optimizeDeps: {
+    include: ["cookie", "marked"]
+  },
+  plugins: [sveltekit()],
+  server: {
+    fs: {
+      allow: [path.resolve("../../../src")]
+    }
+  }
+};
+var vite_config_default = config;
+export {
+  vite_config_default as default
+};
+//# sourceMappingURL=data:application/json;base64,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

From 24b1984b9d2f3ceafa1917facca9f6845fb48619 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 08:22:52 -0400
Subject: [PATCH 02/23] generate __data.js

---
 packages/kit/src/runtime/server/data/index.js | 132 ++++++++++++++
 packages/kit/src/runtime/server/index.js      | 161 +++---------------
 packages/kit/src/runtime/server/page/index.js |   2 +-
 packages/kit/src/runtime/server/utils.js      |   6 +
 4 files changed, 159 insertions(+), 142 deletions(-)
 create mode 100644 packages/kit/src/runtime/server/data/index.js

diff --git a/packages/kit/src/runtime/server/data/index.js b/packages/kit/src/runtime/server/data/index.js
new file mode 100644
index 000000000000..d13611c0a2c1
--- /dev/null
+++ b/packages/kit/src/runtime/server/data/index.js
@@ -0,0 +1,132 @@
+import { HttpError, Redirect } from '../../../index/private.js';
+import { normalize_error } from '../../../utils/error.js';
+import { once } from '../../../utils/functions.js';
+import { load_server_data } from '../page/load_data.js';
+import { error_to_pojo } from '../utils.js';
+import devalue from 'devalue';
+
+/**
+ * @param {import('types').RequestEvent} event
+ * @param {import('types').SSRRoute} route
+ * @param {import('types').SSROptions} options
+ * @param {import('types').SSRState} state
+ * @returns {Promise<Response>}
+ */
+export async function render_data(event, route, options, state) {
+	if (!route.page) {
+		// requesting /__data.js should fail for a +server.js
+		return new Response(undefined, {
+			status: 404
+		});
+	}
+
+	try {
+		const node_ids = [...route.page.layouts, route.page.leaf];
+
+		const invalidated =
+			event.request.headers.get('x-sveltekit-invalidated')?.split(',').map(Boolean) ??
+			node_ids.map(() => true);
+
+		let aborted = false;
+
+		const functions = node_ids.map((n, i) => {
+			return once(async () => {
+				try {
+					if (aborted) {
+						return /** @type {import('types').ServerDataSkippedNode} */ ({
+							type: 'skip'
+						});
+					}
+
+					// == because it could be undefined (in dev) or null (in build, because of JSON.stringify)
+					const node = n == undefined ? n : await options.manifest._.nodes[n]();
+					return load_server_data({
+						event,
+						state,
+						node,
+						parent: async () => {
+							/** @type {Record<string, any>} */
+							const data = {};
+							for (let j = 0; j < i; j += 1) {
+								const parent = /** @type {import('types').ServerDataNode | null} */ (
+									await functions[j]()
+								);
+
+								if (parent) {
+									Object.assign(data, parent.data);
+								}
+							}
+							return data;
+						}
+					});
+				} catch (e) {
+					aborted = true;
+					throw e;
+				}
+			});
+		});
+
+		const promises = functions.map(async (fn, i) => {
+			if (!invalidated[i]) {
+				return /** @type {import('types').ServerDataSkippedNode} */ ({
+					type: 'skip'
+				});
+			}
+
+			return fn();
+		});
+
+		let length = promises.length;
+		const nodes = await Promise.all(
+			promises.map((p, i) =>
+				p.catch((e) => {
+					const error = normalize_error(e);
+
+					if (error instanceof Redirect) {
+						throw error;
+					}
+
+					// Math.min because array isn't guaranteed to resolve in order
+					length = Math.min(length, i + 1);
+
+					if (error instanceof HttpError) {
+						return /** @type {import('types').ServerErrorNode} */ ({
+							type: 'error',
+							httperror: { ...error }
+						});
+					}
+
+					options.handle_error(error, event);
+
+					return /** @type {import('types').ServerErrorNode} */ ({
+						type: 'error',
+						error: error_to_pojo(error, options.get_stack)
+					});
+				})
+			)
+		);
+
+		/** @type {import('types').ServerData} */
+		const server_data = {
+			type: 'data',
+			nodes: nodes.slice(0, length)
+		};
+
+		return new Response(`window.__data = ${devalue(server_data)}`);
+	} catch (e) {
+		const error = normalize_error(e);
+
+		if (error instanceof Redirect) {
+			/** @type {import('types').ServerData} */
+			const server_data = {
+				type: 'redirect',
+				location: error.location
+			};
+
+			return new Response(`window.__data = ${devalue(server_data)}`);
+		} else {
+			// TODO make it clearer that this was an unexpected error
+			return new Response(`window.__data = ${devalue(error_to_pojo(error, options.get_stack))}`);
+		}
+	}
+}
diff --git a/packages/kit/src/runtime/server/index.js b/packages/kit/src/runtime/server/index.js
index f1f2b96cce20..a333587a0a0f 100644
--- a/packages/kit/src/runtime/server/index.js
+++ b/packages/kit/src/runtime/server/index.js
@@ -2,19 +2,16 @@ import { render_endpoint } from './endpoint.js';
 import { render_page } from './page/index.js';
 import { render_response } from './page/render.js';
 import { respond_with_error } from './page/respond_with_error.js';
-import { coalesce_to_error, normalize_error } from '../../utils/error.js';
-import { serialize_error, GENERIC_ERROR, error_to_pojo } from './utils.js';
+import { coalesce_to_error } from '../../utils/error.js';
+import { serialize_error, GENERIC_ERROR } from './utils.js';
 import { decode_params, disable_search, normalize_path } from '../../utils/url.js';
 import { exec } from '../../utils/routing.js';
 import { negotiate } from '../../utils/http.js';
-import { HttpError, Redirect } from '../../index/private.js';
-import { load_server_data } from './page/load_data.js';
-import { json } from '../../index/index.js';
-import { once } from '../../utils/functions.js';
+import { render_data } from './data/index.js';
 
 /* global __SVELTEKIT_ADAPTER_NAME__ */
 
-const DATA_SUFFIX = '/__data.json';
+const DATA_SUFFIX = '/__data.js';
 
 /** @param {{ html: string }} opts */
 const default_transform = ({ html }) => html;
@@ -69,12 +66,7 @@ export async function respond(request, options, state) {
 	}
 
 	const is_data_request = decoded.endsWith(DATA_SUFFIX);
-
-	if (is_data_request) {
-		const data_suffix_length = DATA_SUFFIX.length - (options.trailing_slash === 'always' ? 1 : 0);
-		decoded = decoded.slice(0, -data_suffix_length) || '/';
-		url = new URL(url.origin + url.pathname.slice(0, -data_suffix_length) + url.search);
-	}
+	if (is_data_request) decoded = decoded.slice(0, -DATA_SUFFIX.length);
 
 	if (!state.prerendering?.fallback) {
 		const matchers = await options.manifest._.matchers();
@@ -92,26 +84,19 @@ export async function respond(request, options, state) {
 		}
 	}
 
-	if (route) {
-		if (route.page) {
-			const normalized = normalize_path(url.pathname, options.trailing_slash);
-
-			if (normalized !== url.pathname && !state.prerendering?.fallback) {
-				return new Response(undefined, {
-					status: 301,
-					headers: {
-						'x-sveltekit-normalize': '1',
-						location:
-							// ensure paths starting with '//' are not treated as protocol-relative
-							(normalized.startsWith('//') ? url.origin + normalized : normalized) +
-							(url.search === '?' ? '' : url.search)
-					}
-				});
-			}
-		} else if (is_data_request) {
-			// requesting /__data.json should fail for a standalone endpoint
+	if (route?.page) {
+		const normalized = normalize_path(url.pathname, options.trailing_slash);
+
+		if (normalized !== url.pathname && !state.prerendering?.fallback) {
 			return new Response(undefined, {
-				status: 404
+				status: 301,
+				headers: {
+					'x-sveltekit-normalize': '1',
+					location:
+						// ensure paths starting with '//' are not treated as protocol-relative
+						(normalized.startsWith('//') ? url.origin + normalized : normalized) +
+						(url.search === '?' ? '' : url.search)
+				}
 			});
 		}
 	}
@@ -250,115 +235,9 @@ export async function respond(request, options, state) {
 				if (route) {
 					/** @type {Response} */
 					let response;
-					if (is_data_request && route.page) {
-						try {
-							const node_ids = [...route.page.layouts, route.page.leaf];
-
-							const invalidated =
-								request.headers.get('x-sveltekit-invalidated')?.split(',').map(Boolean) ??
-								node_ids.map(() => true);
-
-							let aborted = false;
-
-							const functions = node_ids.map((n, i) => {
-								return once(async () => {
-									try {
-										if (aborted) {
-											return /** @type {import('types').ServerDataSkippedNode} */ ({
-												type: 'skip'
-											});
-										}
-
-										// == because it could be undefined (in dev) or null (in build, because of JSON.stringify)
-										const node = n == undefined ? n : await options.manifest._.nodes[n]();
-										return load_server_data({
-											event,
-											state,
-											node,
-											parent: async () => {
-												/** @type {Record<string, any>} */
-												const data = {};
-												for (let j = 0; j < i; j += 1) {
-													const parent = /** @type {import('types').ServerDataNode | null} */ (
-														await functions[j]()
-													);
-
-													if (parent) {
-														Object.assign(data, parent.data);
-													}
-												}
-												return data;
-											}
-										});
-									} catch (e) {
-										aborted = true;
-										throw e;
-									}
-								});
-							});
-
-							const promises = functions.map(async (fn, i) => {
-								if (!invalidated[i]) {
-									return /** @type {import('types').ServerDataSkippedNode} */ ({
-										type: 'skip'
-									});
-								}
-
-								return fn();
-							});
 
-							let length = promises.length;
-							const nodes = await Promise.all(
-								promises.map((p, i) =>
-									p.catch((e) => {
-										const error = normalize_error(e);
-
-										if (error instanceof Redirect) {
-											throw error;
-										}
-
-										// Math.min because array isn't guaranteed to resolve in order
-										length = Math.min(length, i + 1);
-
-										if (error instanceof HttpError) {
-											return /** @type {import('types').ServerErrorNode} */ ({
-												type: 'error',
-												httperror: { ...error }
-											});
-										}
-
-										options.handle_error(error, event);
-
-										return /** @type {import('types').ServerErrorNode} */ ({
-											type: 'error',
-											error: error_to_pojo(error, options.get_stack)
-										});
-									})
-								)
-							);
-
-							/** @type {import('types').ServerData} */
-							const server_data = {
-								type: 'data',
-								nodes: nodes.slice(0, length)
-							};
-
-							response = json(server_data);
-						} catch (e) {
-							const error = normalize_error(e);
-
-							if (error instanceof Redirect) {
-								/** @type {import('types').ServerData} */
-								const server_data = {
-									type: 'redirect',
-									location: error.location
-								};
-
-								response = json(server_data);
-							} else {
-								response = json(error_to_pojo(error, options.get_stack), { status: 500 });
-							}
-						}
+					if (is_data_request) {
+						response = await render_data(event, route, options, state);
 					} else if (route.page) {
 						response = await render_page(event, route, route.page, options, state, resolve_opts);
 					} else if (route.endpoint) {
@@ -370,7 +249,7 @@ export async function respond(request, options, state) {
 					}
 
 					if (!is_data_request) {
-						// we only want to set cookies on __data.json requests, we don't
+						// we only want to set cookies on __data.js requests, we don't
 						// want to cache stuff erroneously etc
 						for (const key in headers) {
 							const value = headers[key];
diff --git a/packages/kit/src/runtime/server/page/index.js b/packages/kit/src/runtime/server/page/index.js
index 838fe9342aba..e695f629f174 100644
--- a/packages/kit/src/runtime/server/page/index.js
+++ b/packages/kit/src/runtime/server/page/index.js
@@ -102,7 +102,7 @@ export async function render_page(event, route, page, options, state, resolve_op
 		}
 
 		const should_prerender_data = nodes.some((node) => node?.server);
-		const data_pathname = `${event.url.pathname.replace(/\/$/, '')}/__data.json`;
+		const data_pathname = `${event.url.pathname.replace(/\/$/, '')}/__data.js`;
 
 		// it's crucial that we do this before returning the non-SSR response, otherwise
 		// SvelteKit will erroneously believe that the path has been prerendered,
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index 27fa3abebff5..1edb43f134b3 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -1,3 +1,4 @@
+import devalue from 'devalue';
 import { HttpError } from '../../index/private.js';
 
 /** @param {any} body */
@@ -114,3 +115,8 @@ export function allowed_methods(mod) {
 
 	return allowed;
 }
+
+/** @param {any} data */
+export function data_response(data) {
+	return new Response(`window.__data = ${devalue(data)}`);
+}

From fe30204ffa9d6ce8f8cb61f5e398df36795f67bd Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 10:40:09 -0400
Subject: [PATCH 03/23] wire things up

---
 packages/kit/src/runtime/client/client.js     | 22 +++++++++----------
 packages/kit/src/runtime/server/data/index.js | 16 ++++++++------
 packages/kit/src/runtime/server/utils.js      |  6 ++++-
 3 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 8dd494da3905..e290a1489c50 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -700,20 +700,20 @@ export function create_client({ target, base, trailing_slash }) {
 
 		if (route.uses_server_data && invalid_server_nodes.some(Boolean)) {
 			try {
-				const res = await native_fetch(
-					`${url.pathname}${url.pathname.endsWith('/') ? '' : '/'}__data.json${url.search}`,
-					{
-						headers: {
-							'x-sveltekit-invalidated': invalid_server_nodes.map((x) => (x ? '1' : '')).join(',')
-						}
-					}
+				const data_url = new URL(url);
+				data_url.pathname += `${url.pathname.endsWith('/') ? '' : '/'}__data.js`;
+				data_url.searchParams.set(
+					'__invalid',
+					invalid_server_nodes.map((x) => (x ? 'y' : 'n')).join('')
 				);
 
-				server_data = /** @type {import('types').ServerData} */ (await res.json());
+				await import(/* @vite-ignore */ data_url.href);
 
-				if (!res.ok) {
-					throw server_data;
-				}
+				// @ts-expect-error
+				server_data = /** @type {import('types').ServerData} */ (window.__sveltekit_data);
+
+				// @ts-expect-error
+				delete window.__sveltekit_data;
 			} catch (e) {
 				// something went catastrophically wrong — bail and defer to the server
 				native_navigation(url);
diff --git a/packages/kit/src/runtime/server/data/index.js b/packages/kit/src/runtime/server/data/index.js
index d13611c0a2c1..72a2e1d340b4 100644
--- a/packages/kit/src/runtime/server/data/index.js
+++ b/packages/kit/src/runtime/server/data/index.js
@@ -1,8 +1,8 @@
-import { HttpError, Redirect } from '../../../index/private.js';
+import { HttpError, Redirect } from '../../control.js';
 import { normalize_error } from '../../../utils/error.js';
 import { once } from '../../../utils/functions.js';
 import { load_server_data } from '../page/load_data.js';
-import { error_to_pojo } from '../utils.js';
+import { data_response, error_to_pojo } from '../utils.js';
 import devalue from 'devalue';
 
 /**
@@ -24,8 +24,10 @@ export async function render_data(event, route, options, state) {
 		const node_ids = [...route.page.layouts, route.page.leaf];
 
 		const invalidated =
-			event.request.headers.get('x-sveltekit-invalidated')?.split(',').map(Boolean) ??
-			node_ids.map(() => true);
+			event.url.searchParams
+				.get('__invalid')
+				?.split('')
+				.map((x) => x === 'y') ?? node_ids.map(() => true);
 
 		let aborted = false;
 
@@ -112,7 +114,7 @@ export async function render_data(event, route, options, state) {
 			nodes: nodes.slice(0, length)
 		};
 
-		return new Response(`window.__data = ${devalue(server_data)}`);
+		return data_response(server_data);
 	} catch (e) {
 		const error = normalize_error(e);
 
@@ -123,10 +125,10 @@ export async function render_data(event, route, options, state) {
 				location: error.location
 			};
 
-			return new Response(`window.__data = ${devalue(server_data)}`);
+			return data_response(server_data);
 		} else {
 			// TODO make it clearer that this was an unexpected error
-			return new Response(`window.__data = ${devalue(error_to_pojo(error, options.get_stack))}`);
+			return data_response(error_to_pojo(error, options.get_stack));
 		}
 	}
 }
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index dd9947182928..2416b38d9583 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -118,5 +118,9 @@ export function allowed_methods(mod) {
 
 /** @param {any} data */
 export function data_response(data) {
-	return new Response(`window.__data = ${devalue(data)}`);
+	return new Response(`window.__sveltekit_data = ${devalue(data)}`, {
+		headers: {
+			'content-type': 'application/javascript'
+		}
+	});
 }

From fb0621f3ae72b871e6d5d5483a1a38e5bb92badc Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 11:08:23 -0400
Subject: [PATCH 04/23] fix

---
 packages/kit/src/{core => }/constants.js      |  2 +
 packages/kit/src/core/env.js                  |  2 +-
 packages/kit/src/core/sync/write_ambient.js   |  2 +-
 packages/kit/src/exports/vite/dev/index.js    |  2 +-
 .../kit/src/exports/vite/preview/index.js     |  2 +-
 packages/kit/src/runtime/client/client.js     | 57 +++++++++++--------
 packages/kit/src/runtime/server/data/index.js | 14 ++++-
 packages/kit/src/runtime/server/index.js      |  3 +-
 packages/kit/test/apps/basics/test/test.js    |  4 +-
 9 files changed, 54 insertions(+), 34 deletions(-)
 rename packages/kit/src/{core => }/constants.js (87%)

diff --git a/packages/kit/src/core/constants.js b/packages/kit/src/constants.js
similarity index 87%
rename from packages/kit/src/core/constants.js
rename to packages/kit/src/constants.js
index 8dc9aab27904..7d50f152432c 100644
--- a/packages/kit/src/core/constants.js
+++ b/packages/kit/src/constants.js
@@ -3,3 +3,5 @@
 export const SVELTE_KIT_ASSETS = '/_svelte_kit_assets';
 
 export const GENERATED_COMMENT = '// this file is generated — do not edit it\n';
+
+export const DATA_SUFFIX = '/__data.js';
diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index 2d2006098283..789348a62cd7 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -1,4 +1,4 @@
-import { GENERATED_COMMENT } from './constants.js';
+import { GENERATED_COMMENT } from '../constants.js';
 import { runtime_base } from './utils.js';
 
 /**
diff --git a/packages/kit/src/core/sync/write_ambient.js b/packages/kit/src/core/sync/write_ambient.js
index 9672488bb2f2..9904a1cee043 100644
--- a/packages/kit/src/core/sync/write_ambient.js
+++ b/packages/kit/src/core/sync/write_ambient.js
@@ -1,6 +1,6 @@
 import path from 'path';
 import { get_env } from '../../exports/vite/utils.js';
-import { GENERATED_COMMENT } from '../constants.js';
+import { GENERATED_COMMENT } from '../../constants.js';
 import { create_types } from '../env.js';
 import { write_if_changed } from './utils.js';
 
diff --git a/packages/kit/src/exports/vite/dev/index.js b/packages/kit/src/exports/vite/dev/index.js
index 77cb0bfb9e86..a74cdddd20ed 100644
--- a/packages/kit/src/exports/vite/dev/index.js
+++ b/packages/kit/src/exports/vite/dev/index.js
@@ -8,7 +8,7 @@ import { installPolyfills } from '../../../exports/node/polyfills.js';
 import { coalesce_to_error } from '../../../utils/error.js';
 import { posixify } from '../../../utils/filesystem.js';
 import { load_template } from '../../../core/config/index.js';
-import { SVELTE_KIT_ASSETS } from '../../../core/constants.js';
+import { SVELTE_KIT_ASSETS } from '../../../constants.js';
 import * as sync from '../../../core/sync/sync.js';
 import { get_mime_lookup, runtime_base, runtime_prefix } from '../../../core/utils.js';
 import { get_env, prevent_illegal_vite_imports, resolve_entry } from '../utils.js';
diff --git a/packages/kit/src/exports/vite/preview/index.js b/packages/kit/src/exports/vite/preview/index.js
index 54539d3e03c5..9f1a80298e77 100644
--- a/packages/kit/src/exports/vite/preview/index.js
+++ b/packages/kit/src/exports/vite/preview/index.js
@@ -4,7 +4,7 @@ import sirv from 'sirv';
 import { pathToFileURL } from 'url';
 import { getRequest, setResponse } from '../../../exports/node/index.js';
 import { installPolyfills } from '../../../exports/node/polyfills.js';
-import { SVELTE_KIT_ASSETS } from '../../../core/constants.js';
+import { SVELTE_KIT_ASSETS } from '../../../constants.js';
 import { loadEnv } from 'vite';
 
 /** @typedef {import('http').IncomingMessage} Req */
diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index e290a1489c50..3f4153e0e41c 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -700,20 +700,7 @@ export function create_client({ target, base, trailing_slash }) {
 
 		if (route.uses_server_data && invalid_server_nodes.some(Boolean)) {
 			try {
-				const data_url = new URL(url);
-				data_url.pathname += `${url.pathname.endsWith('/') ? '' : '/'}__data.js`;
-				data_url.searchParams.set(
-					'__invalid',
-					invalid_server_nodes.map((x) => (x ? 'y' : 'n')).join('')
-				);
-
-				await import(/* @vite-ignore */ data_url.href);
-
-				// @ts-expect-error
-				server_data = /** @type {import('types').ServerData} */ (window.__sveltekit_data);
-
-				// @ts-expect-error
-				delete window.__sveltekit_data;
+				server_data = await load_data(url, invalid_server_nodes);
 			} catch (e) {
 				// something went catastrophically wrong — bail and defer to the server
 				native_navigation(url);
@@ -868,19 +855,18 @@ export function create_client({ target, base, trailing_slash }) {
 		if (node.server) {
 			// TODO post-https://github.com/sveltejs/kit/discussions/6124 we can use
 			// existing root layout data
-			const res = await native_fetch(
-				`${url.pathname}${url.pathname.endsWith('/') ? '' : '/'}__data.json${url.search}`,
-				{
-					headers: {
-						'x-sveltekit-invalidated': '1'
-					}
-				}
-			);
+			try {
+				const server_data = await load_data(url, [true]);
 
-			const server_data_nodes = await res.json();
-			server_data_node = server_data_nodes?.[0] ?? null;
+				if (
+					server_data.type !== 'data' ||
+					(server_data.nodes[0] && server_data.nodes[0].type !== 'data')
+				) {
+					throw 0;
+				}
 
-			if (!res.ok || server_data_nodes?.type !== 'data') {
+				server_data_node = server_data.nodes[0] ?? null;
+			} catch {
 				// at this point we have no choice but to fall back to the server
 				native_navigation(url);
 
@@ -1353,3 +1339,24 @@ export function create_client({ target, base, trailing_slash }) {
 		}
 	};
 }
+
+/**
+ * @param {URL} url
+ * @param {boolean[]} invalid
+ * @returns {Promise<import('types').ServerData>}
+ */
+async function load_data(url, invalid) {
+	const data_url = new URL(url);
+	data_url.pathname += `${url.pathname.endsWith('/') ? '' : '/'}__data.js`;
+	data_url.searchParams.set('__invalid', invalid.map((x) => (x ? 'y' : 'n')).join(''));
+
+	await import(/* @vite-ignore */ data_url.href);
+
+	// @ts-expect-error
+	const server_data = window.__sveltekit_data;
+
+	// @ts-expect-error
+	delete window.__sveltekit_data;
+
+	return server_data;
+}
diff --git a/packages/kit/src/runtime/server/data/index.js b/packages/kit/src/runtime/server/data/index.js
index 72a2e1d340b4..9b09e49785b3 100644
--- a/packages/kit/src/runtime/server/data/index.js
+++ b/packages/kit/src/runtime/server/data/index.js
@@ -4,6 +4,8 @@ import { once } from '../../../utils/functions.js';
 import { load_server_data } from '../page/load_data.js';
 import { data_response, error_to_pojo } from '../utils.js';
 import devalue from 'devalue';
+import { normalize_path } from '../../../utils/url.js';
+import { DATA_SUFFIX } from '../../../constants.js';
 
 /**
  * @param {import('types').RequestEvent} event
@@ -31,6 +33,16 @@ export async function render_data(event, route, options, state) {
 
 		let aborted = false;
 
+		const url = new URL(event.url);
+		url.pathname = normalize_path(
+			url.pathname.slice(0, -DATA_SUFFIX.length),
+			options.trailing_slash
+		);
+
+		url.searchParams.delete('__invalid');
+
+		const new_event = { ...event, url };
+
 		const functions = node_ids.map((n, i) => {
 			return once(async () => {
 				try {
@@ -43,7 +55,7 @@ export async function render_data(event, route, options, state) {
 					// == because it could be undefined (in dev) or null (in build, because of JSON.stringify)
 					const node = n == undefined ? n : await options.manifest._.nodes[n]();
 					return load_server_data({
-						event,
+						event: new_event,
 						state,
 						node,
 						parent: async () => {
diff --git a/packages/kit/src/runtime/server/index.js b/packages/kit/src/runtime/server/index.js
index a333587a0a0f..c87cf264a73e 100644
--- a/packages/kit/src/runtime/server/index.js
+++ b/packages/kit/src/runtime/server/index.js
@@ -8,11 +8,10 @@ import { decode_params, disable_search, normalize_path } from '../../utils/url.j
 import { exec } from '../../utils/routing.js';
 import { negotiate } from '../../utils/http.js';
 import { render_data } from './data/index.js';
+import { DATA_SUFFIX } from '../../constants.js';
 
 /* global __SVELTEKIT_ADAPTER_NAME__ */
 
-const DATA_SUFFIX = '/__data.js';
-
 /** @param {{ html: string }} opts */
 const default_transform = ({ html }) => html;
 
diff --git a/packages/kit/test/apps/basics/test/test.js b/packages/kit/test/apps/basics/test/test.js
index 497a409a3fec..a10a1ad9545c 100644
--- a/packages/kit/test/apps/basics/test/test.js
+++ b/packages/kit/test/apps/basics/test/test.js
@@ -893,11 +893,11 @@ test.describe('Load', () => {
 		expect(await page.textContent('h2')).toBe('pagedata: pagedata');
 	});
 
-	test.only('Serializes non-JSON data', async ({ page, clicknav }) => {
+	test('Serializes non-JSON data', async ({ page, clicknav }) => {
 		await page.goto('/load/devalue');
 		await clicknav('[href="/load/devalue/regex"]');
 
-		expect(await page.textContent('h1')).toBe(true);
+		expect(await page.textContent('h1')).toBe('true');
 	});
 });
 

From 35de03c80d0633508c087a7dca0e5e34439a6a42 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 13:18:22 -0400
Subject: [PATCH 05/23] update devalue

---
 packages/kit/package.json                      | 2 +-
 packages/kit/src/runtime/server/data/index.js  | 1 -
 packages/kit/src/runtime/server/page/render.js | 2 +-
 packages/kit/src/runtime/server/utils.js       | 2 +-
 pnpm-lock.yaml                                 | 8 ++++----
 5 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/packages/kit/package.json b/packages/kit/package.json
index ec73fb650ddb..4a1b1fd3c6e5 100644
--- a/packages/kit/package.json
+++ b/packages/kit/package.json
@@ -12,7 +12,7 @@
 	"dependencies": {
 		"@sveltejs/vite-plugin-svelte": "^1.0.1",
 		"cookie": "^0.5.0",
-		"devalue": "^2.0.1",
+		"devalue": "^3.0.1",
 		"kleur": "^4.1.4",
 		"magic-string": "^0.26.2",
 		"mime": "^3.0.0",
diff --git a/packages/kit/src/runtime/server/data/index.js b/packages/kit/src/runtime/server/data/index.js
index 9b09e49785b3..32cb9baed05e 100644
--- a/packages/kit/src/runtime/server/data/index.js
+++ b/packages/kit/src/runtime/server/data/index.js
@@ -3,7 +3,6 @@ import { normalize_error } from '../../../utils/error.js';
 import { once } from '../../../utils/functions.js';
 import { load_server_data } from '../page/load_data.js';
 import { data_response, error_to_pojo } from '../utils.js';
-import devalue from 'devalue';
 import { normalize_path } from '../../../utils/url.js';
 import { DATA_SUFFIX } from '../../../constants.js';
 
diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
index b801ee0509d7..3499b1a91561 100644
--- a/packages/kit/src/runtime/server/page/render.js
+++ b/packages/kit/src/runtime/server/page/render.js
@@ -1,4 +1,4 @@
-import devalue from 'devalue';
+import { devalue } from 'devalue';
 import { readable, writable } from 'svelte/store';
 import * as cookie from 'cookie';
 import { hash } from '../../hash.js';
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index 2416b38d9583..4e18a8ba68e0 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -1,4 +1,4 @@
-import devalue from 'devalue';
+import { devalue } from 'devalue';
 import { HttpError } from '../control.js';
 
 /** @param {any} body */
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0967ad4444da..e97070a7194c 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -278,7 +278,7 @@ importers:
       '@types/sade': ^1.7.4
       '@types/set-cookie-parser': ^2.4.2
       cookie: ^0.5.0
-      devalue: ^2.0.1
+      devalue: ^3.0.1
       kleur: ^4.1.4
       magic-string: ^0.26.2
       marked: ^4.0.16
@@ -298,7 +298,7 @@ importers:
     dependencies:
       '@sveltejs/vite-plugin-svelte': 1.0.1_svelte@3.48.0+vite@3.0.9
       cookie: 0.5.0
-      devalue: 2.0.1
+      devalue: 3.0.1
       kleur: 4.1.5
       magic-string: 0.26.2
       mime: 3.0.0
@@ -1748,8 +1748,8 @@ packages:
     resolution: {integrity: sha512-463v3ZeIrcWtdgIg6vI6XUncguvr2TnGl4SzDXinkt9mSLpBJKXT3mW6xT3VQdDN11+WVs29pgvivTc4Lp8v+w==}
     engines: {node: '>=8'}
 
-  /devalue/2.0.1:
-    resolution: {integrity: sha512-I2TiqT5iWBEyB8GRfTDP0hiLZ0YeDJZ+upDxjBfOC2lebO5LezQMv7QvIUTzdb64jQyAKLf1AHADtGN+jw6v8Q==}
+  /devalue/3.0.1:
+    resolution: {integrity: sha512-c6cNErg/5JNdvh/EcgjQZ3h4Pyy5MXy/GMMv/dENJ1l5zwr+e3yKGZo5NmtpsDCcF5QW0u1ifxMnbH2GiEAIwg==}
     dev: false
 
   /diff/5.1.0:

From 3e8ec03e1e9c32a5aa102a0e9ac654f9eb058ebc Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 13:23:28 -0400
Subject: [PATCH 06/23] cachebust

---
 packages/kit/src/runtime/client/client.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 3f4153e0e41c..93d9142793b1 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -1340,6 +1340,8 @@ export function create_client({ target, base, trailing_slash }) {
 	};
 }
 
+let data_id = 1;
+
 /**
  * @param {URL} url
  * @param {boolean[]} invalid
@@ -1349,6 +1351,7 @@ async function load_data(url, invalid) {
 	const data_url = new URL(url);
 	data_url.pathname += `${url.pathname.endsWith('/') ? '' : '/'}__data.js`;
 	data_url.searchParams.set('__invalid', invalid.map((x) => (x ? 'y' : 'n')).join(''));
+	data_url.searchParams.set('__id', String(data_id++));
 
 	await import(/* @vite-ignore */ data_url.href);
 

From e30390024b30e4329bef201762528aaefbd01d4c Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 14:17:33 -0400
Subject: [PATCH 07/23] get it working

---
 packages/kit/package.json                     |  2 +-
 packages/kit/src/runtime/server/data/index.js |  1 +
 .../kit/src/runtime/server/page/render.js     | 23 +++++++++++++++++++
 packages/kit/src/runtime/server/utils.js      | 18 +++++++++++----
 .../shadowed/serialization/+page.server.js    |  8 ++++++-
 .../shadowed/serialization/+page.svelte       |  2 +-
 packages/kit/test/apps/basics/test/test.js    |  4 ++--
 pnpm-lock.yaml                                |  8 +++----
 8 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/packages/kit/package.json b/packages/kit/package.json
index 4a1b1fd3c6e5..715a294a8044 100644
--- a/packages/kit/package.json
+++ b/packages/kit/package.json
@@ -12,7 +12,7 @@
 	"dependencies": {
 		"@sveltejs/vite-plugin-svelte": "^1.0.1",
 		"cookie": "^0.5.0",
-		"devalue": "^3.0.1",
+		"devalue": "^3.1.0",
 		"kleur": "^4.1.4",
 		"magic-string": "^0.26.2",
 		"mime": "^3.0.0",
diff --git a/packages/kit/src/runtime/server/data/index.js b/packages/kit/src/runtime/server/data/index.js
index 32cb9baed05e..25296344fca5 100644
--- a/packages/kit/src/runtime/server/data/index.js
+++ b/packages/kit/src/runtime/server/data/index.js
@@ -39,6 +39,7 @@ export async function render_data(event, route, options, state) {
 		);
 
 		url.searchParams.delete('__invalid');
+		url.searchParams.delete('__id');
 
 		const new_event = { ...event, url };
 
diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
index 3499b1a91561..a2574aeaf879 100644
--- a/packages/kit/src/runtime/server/page/render.js
+++ b/packages/kit/src/runtime/server/page/render.js
@@ -174,6 +174,29 @@ export async function render_response({
 	/** @param {string} path */
 	const prefixed = (path) => (path.startsWith('/') ? path : `${assets}/${path}`);
 
+	const serialized = { data: '', errors: 'null' };
+
+	try {
+		serialized.data = devalue(branch.map(({ server_data }) => server_data));
+	} catch (e) {
+		// TODO if we wanted to get super fancy we could track down the origin of the `load`
+		// function, but it would mean passing more stuff around than we currently do
+		const error = /** @type {any} */ (e);
+		const match = /\[(\d+)\]\.data\.(.+)/.exec(error.path);
+		if (match) throw new Error(`${error.message} (data.${match[2]})`);
+		throw error;
+	}
+
+	if (validation_errors) {
+		try {
+			serialized.errors = devalue(validation_errors);
+		} catch (e) {
+			const error = /** @type {any} */ (e);
+			if (error.path) throw new Error(`${error.message} (errors.${error.path})`);
+			throw error;
+		}
+	}
+
 	// prettier-ignore
 	const init_app = `
 		import { set_public_env, start } from ${s(prefixed(entry.file))};
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index 4e18a8ba68e0..2c2b7a399ced 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -118,9 +118,17 @@ export function allowed_methods(mod) {
 
 /** @param {any} data */
 export function data_response(data) {
-	return new Response(`window.__sveltekit_data = ${devalue(data)}`, {
-		headers: {
-			'content-type': 'application/javascript'
-		}
-	});
+	try {
+		return new Response(`window.__sveltekit_data = ${devalue(data)}`, {
+			headers: {
+				'content-type': 'application/javascript'
+			}
+		});
+	} catch (e) {
+		return new Response(`throw new Error(${JSON.stringify(e.message)})`, {
+			headers: {
+				'content-type': 'application/javascript'
+			}
+		});
+	}
 }
diff --git a/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js b/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js
index ceb16a88757e..47e76245eb40 100644
--- a/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js
+++ b/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js
@@ -1,5 +1,11 @@
+class Nope {
+	toString() {
+		return 'should not see me'
+	}
+}
+
 export function load() {
 	return {
-		regex: /nope/
+		nope: new Nope()
 	};
 }
diff --git a/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.svelte b/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.svelte
index a5a2d66e7841..f8a4718b5545 100644
--- a/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.svelte
+++ b/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.svelte
@@ -3,4 +3,4 @@
 	export let data;
 </script>
 
-<h1>{data.regex.test('nope')}</h1>
+<h1>{data.nope}</h1>
diff --git a/packages/kit/test/apps/basics/test/test.js b/packages/kit/test/apps/basics/test/test.js
index a10a1ad9545c..c659740d2f98 100644
--- a/packages/kit/test/apps/basics/test/test.js
+++ b/packages/kit/test/apps/basics/test/test.js
@@ -291,7 +291,7 @@ test.describe('Shadowed pages', () => {
 
 			expect(await page.textContent('h1')).toBe('500');
 			expect(await page.textContent('#message')).toBe(
-				'This is your custom error page saying: "data.regex returned from \'load\' in src/routes/shadowed/serialization/+page.server.js cannot be serialized as JSON"'
+				'This is your custom error page saying: "Cannot stringify arbitrary non-POJOs (data.nope)"'
 			);
 		});
 	}
@@ -579,7 +579,7 @@ test.describe('Errors', () => {
 			expect(lines[1]).toContain('+page.server.js:4:8');
 		}
 
-		const error = read_errors('/errors/page-endpoint/get-implicit');
+		const error = read_errors('/errors/page-endpoint/get-implicit/__data.js');
 		expect(error).toContain('oops');
 	});
 
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index e97070a7194c..540d46a08b15 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -278,7 +278,7 @@ importers:
       '@types/sade': ^1.7.4
       '@types/set-cookie-parser': ^2.4.2
       cookie: ^0.5.0
-      devalue: ^3.0.1
+      devalue: ^3.1.0
       kleur: ^4.1.4
       magic-string: ^0.26.2
       marked: ^4.0.16
@@ -298,7 +298,7 @@ importers:
     dependencies:
       '@sveltejs/vite-plugin-svelte': 1.0.1_svelte@3.48.0+vite@3.0.9
       cookie: 0.5.0
-      devalue: 3.0.1
+      devalue: 3.1.0
       kleur: 4.1.5
       magic-string: 0.26.2
       mime: 3.0.0
@@ -1748,8 +1748,8 @@ packages:
     resolution: {integrity: sha512-463v3ZeIrcWtdgIg6vI6XUncguvr2TnGl4SzDXinkt9mSLpBJKXT3mW6xT3VQdDN11+WVs29pgvivTc4Lp8v+w==}
     engines: {node: '>=8'}
 
-  /devalue/3.0.1:
-    resolution: {integrity: sha512-c6cNErg/5JNdvh/EcgjQZ3h4Pyy5MXy/GMMv/dENJ1l5zwr+e3yKGZo5NmtpsDCcF5QW0u1ifxMnbH2GiEAIwg==}
+  /devalue/3.1.0:
+    resolution: {integrity: sha512-5Nb73BzNSGvDJNWCVXHv9R+rhNg0pN+OsgeJ/BRYCvMsEBCDfP9Ci/5cHjSPoOSMWBrh3MtUDQtChfdKYWLxeg==}
     dev: false
 
   /diff/5.1.0:

From 401c02d0705f30adf0cfe9c119b96bf422aa256a Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 14:20:57 -0400
Subject: [PATCH 08/23] huh

---
 ...vite.config.js.timestamp-1661481874774.mjs | 23 -------------------
 1 file changed, 23 deletions(-)
 delete mode 100644 packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs

diff --git a/packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs b/packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs
deleted file mode 100644
index d0793c197a93..000000000000
--- a/packages/kit/test/apps/basics/vite.config.js.timestamp-1661481874774.mjs
+++ /dev/null
@@ -1,23 +0,0 @@
-// vite.config.js
-import * as path from "path";
-import { sveltekit } from "@sveltejs/kit/vite";
-var config = {
-  build: {
-    minify: false
-  },
-  clearScreen: false,
-  optimizeDeps: {
-    include: ["cookie", "marked"]
-  },
-  plugins: [sveltekit()],
-  server: {
-    fs: {
-      allow: [path.resolve("../../../src")]
-    }
-  }
-};
-var vite_config_default = config;
-export {
-  vite_config_default as default
-};
-//# sourceMappingURL=data:application/json;base64,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

From 31010dc136f11b3ed52f4a58415bc472cb31cf45 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 14:35:48 -0400
Subject: [PATCH 09/23] fixes

---
 packages/adapter-netlify/index.js             |  2 +-
 packages/adapter-vercel/index.js              |  2 +-
 packages/kit/src/runtime/server/page/index.js | 25 +++---
 packages/kit/test/apps/options/test/test.js   | 14 ++--
 .../kit/test/prerendering/basics/test/test.js | 84 ++++++++++++-------
 .../prerendering/trailing-slash/test/test.js  |  2 +-
 6 files changed, 79 insertions(+), 50 deletions(-)

diff --git a/packages/adapter-netlify/index.js b/packages/adapter-netlify/index.js
index 39bc32738954..4528b8a3c6a6 100644
--- a/packages/adapter-netlify/index.js
+++ b/packages/adapter-netlify/index.js
@@ -211,7 +211,7 @@ async function generate_lambda_functions({ builder, publish, split, esm }) {
 					writeFileSync(`.netlify/functions-internal/${name}.js`, fn);
 
 					redirects.push(`${pattern} /.netlify/functions/${name} 200`);
-					redirects.push(`${pattern}/__data.json /.netlify/functions/${name} 200`);
+					redirects.push(`${pattern}/__data.js /.netlify/functions/${name} 200`);
 				}
 			};
 		});
diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 532d3534e20a..0d0ba443385c 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -224,7 +224,7 @@ export default function ({ external = [], edge, split } = {}) {
 								sliced_pattern = '^/?';
 							}
 
-							const src = `${sliced_pattern}(?:/__data.json)?$`; // TODO adding /__data.json is a temporary workaround — those endpoints should be treated as distinct routes
+							const src = `${sliced_pattern}(?:/__data.js)?$`; // TODO adding /__data.js is a temporary workaround — those endpoints should be treated as distinct routes
 
 							await generate_function(route.id || 'index', src, entry.generateManifest);
 						}
diff --git a/packages/kit/src/runtime/server/page/index.js b/packages/kit/src/runtime/server/page/index.js
index 8c6d390afea4..e29b5eb6e8cc 100644
--- a/packages/kit/src/runtime/server/page/index.js
+++ b/packages/kit/src/runtime/server/page/index.js
@@ -1,3 +1,4 @@
+import { devalue } from 'devalue';
 import { negotiate } from '../../../utils/http.js';
 import { render_response } from './render.js';
 import { respond_with_error } from './respond_with_error.js';
@@ -230,12 +231,14 @@ export async function render_page(event, route, page, options, state, resolve_op
 
 					if (error instanceof Redirect) {
 						if (state.prerendering && should_prerender_data) {
+							const body = `window.__sveltekit_data = ${JSON.stringify({
+								type: 'redirect',
+								location: error.location
+							})}`;
+
 							state.prerendering.dependencies.set(data_pathname, {
-								response: new Response(undefined),
-								body: JSON.stringify({
-									type: 'redirect',
-									location: error.location
-								})
+								response: new Response(body),
+								body
 							});
 						}
 
@@ -293,12 +296,14 @@ export async function render_page(event, route, page, options, state, resolve_op
 		}
 
 		if (state.prerendering && should_prerender_data) {
+			const body = `window.__sveltekit_data = ${devalue({
+				type: 'data',
+				nodes: branch.map((branch_node) => branch_node?.server_data)
+			})}`;
+
 			state.prerendering.dependencies.set(data_pathname, {
-				response: new Response(undefined),
-				body: JSON.stringify({
-					type: 'data',
-					nodes: branch.map((branch_node) => branch_node?.server_data)
-				})
+				response: new Response(body),
+				body
 			});
 		}
 
diff --git a/packages/kit/test/apps/options/test/test.js b/packages/kit/test/apps/options/test/test.js
index cfd4e364652f..61cef9a29256 100644
--- a/packages/kit/test/apps/options/test/test.js
+++ b/packages/kit/test/apps/options/test/test.js
@@ -163,10 +163,14 @@ test.describe('trailingSlash', () => {
 		expect(await r2.text()).toBe('hi');
 	});
 
-	test('can fetch data from page-endpoint', async ({ request, baseURL }) => {
-		const r = await request.get('/path-base/page-endpoint/__data.json');
-		expect(r.url()).toBe(`${baseURL}/path-base/page-endpoint/__data.json`);
-		expect(await r.json()).toEqual({
+	test('can fetch data from page-endpoint', async ({ request }) => {
+		const r = await request.get('/path-base/page-endpoint/__data.js');
+		const code = await r.text();
+
+		const window = {};
+		new Function('window', code)(window);
+
+		expect(window.__sveltekit_data).toEqual({
 			type: 'data',
 			nodes: [null, { type: 'data', data: { message: 'hi' }, uses: {} }]
 		});
@@ -197,7 +201,7 @@ test.describe('trailingSlash', () => {
 			expect(requests.filter((req) => req.endsWith('.js')).length).toBeGreaterThan(0);
 		}
 
-		expect(requests.includes(`${baseURL}/path-base/prefetching/prefetched/__data.json`)).toBe(true);
+		expect(requests.includes(`${baseURL}/path-base/prefetching/prefetched/__data.js`)).toBe(true);
 
 		requests = [];
 		await app.goto('/path-base/prefetching/prefetched');
diff --git a/packages/kit/test/prerendering/basics/test/test.js b/packages/kit/test/prerendering/basics/test/test.js
index 2a450e9650b4..32d09321a2e2 100644
--- a/packages/kit/test/prerendering/basics/test/test.js
+++ b/packages/kit/test/prerendering/basics/test/test.js
@@ -25,14 +25,14 @@ test('renders a server-side redirect', () => {
 	const html = read('redirect-server.html');
 	assert.equal(html, '<meta http-equiv="refresh" content="0;url=https://example.com/redirected">');
 
-	const json = read('redirect-server/__data.json');
-	assert.equal(
-		json,
-		JSON.stringify({
-			type: 'redirect',
-			location: 'https://example.com/redirected'
-		})
-	);
+	const code = read('redirect-server/__data.js');
+	const window = {};
+	new Function('window', `(${code})`)(window);
+
+	assert.equal(window.__sveltekit_data, {
+		type: 'redirect',
+		location: 'https://example.com/redirected'
+	});
 });
 
 test('does not double-encode redirect locations', () => {
@@ -77,31 +77,44 @@ test('loads a file with spaces in the filename', () => {
 	assert.ok(content.includes('<h1>answer: 42</h1>'), content);
 });
 
-test('generates __data.json file for shadow endpoints', () => {
-	assert.equal(
-		read('__data.json'),
-		JSON.stringify({
-			type: 'data',
-			nodes: [null, { type: 'data', data: { message: 'hello' }, uses: {} }]
-		})
-	);
-	assert.equal(
-		read('shadowed-get/__data.json'),
-		JSON.stringify({
-			type: 'data',
-			nodes: [null, { type: 'data', data: { answer: 42 }, uses: {} }]
-		})
-	);
+test('generates __data.js file for shadow endpoints', () => {
+	const window = {};
+
+	new Function('window', read('__data.js'))(window);
+	assert.equal(window.__sveltekit_data, {
+		type: 'data',
+		nodes: [
+			null,
+			{
+				type: 'data',
+				data: { message: 'hello' },
+				uses: { dependencies: undefined, params: undefined, parent: undefined, url: undefined }
+			}
+		]
+	});
+
+	new Function('window', read('shadowed-get/__data.js'))(window);
+	assert.equal(window.__sveltekit_data, {
+		type: 'data',
+		nodes: [
+			null,
+			{
+				type: 'data',
+				data: { answer: 42 },
+				uses: { dependencies: undefined, params: undefined, parent: undefined, url: undefined }
+			}
+		]
+	});
 });
 
 test('does not prerender page with shadow endpoint with non-load handler', () => {
 	assert.ok(!fs.existsSync(`${build}/shadowed-post.html`));
-	assert.ok(!fs.existsSync(`${build}/shadowed-post/__data.json`));
+	assert.ok(!fs.existsSync(`${build}/shadowed-post/__data.js`));
 });
 
 test('does not prerender page with prerender = false in +page.server.js', () => {
 	assert.ok(!fs.existsSync(`${build}/page-server-options.html`));
-	assert.ok(!fs.existsSync(`${build}/page-server-options/__data.json`));
+	assert.ok(!fs.existsSync(`${build}/page-server-options/__data.js`));
 });
 
 test('decodes paths when writing files', () => {
@@ -175,13 +188,20 @@ test('prerenders binary data', async () => {
 });
 
 test('fetches data from local endpoint', () => {
-	assert.equal(
-		read('origin/__data.json'),
-		JSON.stringify({
-			type: 'data',
-			nodes: [null, { type: 'data', data: { message: 'hello' }, uses: {} }]
-		})
-	);
+	const window = {};
+	new Function('window', read('origin/__data.js'))(window);
+
+	assert.equal(window.__sveltekit_data, {
+		type: 'data',
+		nodes: [
+			null,
+			{
+				type: 'data',
+				data: { message: 'hello' },
+				uses: { dependencies: undefined, params: undefined, parent: undefined, url: undefined }
+			}
+		]
+	});
 	assert.equal(read('origin/message.json'), JSON.stringify({ message: 'hello' }));
 });
 
diff --git a/packages/kit/test/prerendering/trailing-slash/test/test.js b/packages/kit/test/prerendering/trailing-slash/test/test.js
index 8a7c6550a3f9..0344b61298ef 100644
--- a/packages/kit/test/prerendering/trailing-slash/test/test.js
+++ b/packages/kit/test/prerendering/trailing-slash/test/test.js
@@ -11,7 +11,7 @@ const read = (file) => fs.readFileSync(`${build}/${file}`, 'utf-8');
 test('prerendered.paths omits trailing slashes for endpoints', () => {
 	const content = read('service-worker.js');
 
-	for (const path of ['/page/', '/page/__data.json', '/standalone-endpoint.json']) {
+	for (const path of ['/page/', '/page/__data.js', '/standalone-endpoint.json']) {
 		assert.ok(content.includes(`"${path}"`), `Missing ${path}`);
 	}
 });

From 978d0d41a8526ae286f8b19d8e14b344647f7264 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 14:38:02 -0400
Subject: [PATCH 10/23] lint

---
 .../basics/src/routes/shadowed/serialization/+page.server.js    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js b/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js
index 47e76245eb40..ee20c2cc975f 100644
--- a/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js
+++ b/packages/kit/test/apps/basics/src/routes/shadowed/serialization/+page.server.js
@@ -1,6 +1,6 @@
 class Nope {
 	toString() {
-		return 'should not see me'
+		return 'should not see me';
 	}
 }
 

From 8481a6a3a42888cf044cdfa7f0576dcf387aa0e1 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 14:48:36 -0400
Subject: [PATCH 11/23] fixes

---
 packages/kit/package.json                  |  2 +-
 packages/kit/src/runtime/client/client.js  | 26 ++++++++++++++++------
 packages/kit/src/runtime/client/types.d.ts |  2 +-
 pnpm-lock.yaml                             |  8 +++----
 4 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/packages/kit/package.json b/packages/kit/package.json
index 715a294a8044..5b2d59a246a0 100644
--- a/packages/kit/package.json
+++ b/packages/kit/package.json
@@ -12,7 +12,7 @@
 	"dependencies": {
 		"@sveltejs/vite-plugin-svelte": "^1.0.1",
 		"cookie": "^0.5.0",
-		"devalue": "^3.1.0",
+		"devalue": "^3.1.1",
 		"kleur": "^4.1.4",
 		"magic-string": "^0.26.2",
 		"mime": "^3.0.0",
diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 93d9142793b1..ba81b3922940 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -393,7 +393,7 @@ export function create_client({ target, base, trailing_slash }) {
 	 *   status: number;
 	 *   error: HttpError | Error | null;
 	 *   routeId: string | null;
-	 *   validation_errors?: string | undefined;
+	 *   validation_errors?: Record<string, any> | null;
 	 * }} opts
 	 */
 	async function get_navigation_result_from_branch({
@@ -1272,7 +1272,7 @@ export function create_client({ target, base, trailing_slash }) {
 
 		_hydrate: async ({
 			status,
-			error,
+			error: original_error, // TODO get rid of this
 			node_ids,
 			params,
 			routeId,
@@ -1286,6 +1286,16 @@ export function create_client({ target, base, trailing_slash }) {
 
 			try {
 				const branch_promises = node_ids.map(async (n, i) => {
+					const server_data_node = server_data_nodes[i];
+
+					if (server_data_node?.type === 'error') {
+						if (server_data_node.httperror) {
+							throw error(server_data_node.httperror.status, server_data_node.httperror.message);
+						}
+
+						throw server_data_node.error;
+					}
+
 					return load_node({
 						loader: nodes[n],
 						url,
@@ -1298,7 +1308,7 @@ export function create_client({ target, base, trailing_slash }) {
 							}
 							return data;
 						},
-						server_data_node: create_data_node(server_data_nodes[i])
+						server_data_node: create_data_node(server_data_node)
 					});
 				});
 
@@ -1307,13 +1317,15 @@ export function create_client({ target, base, trailing_slash }) {
 					params,
 					branch: await Promise.all(branch_promises),
 					status,
-					error: /** @type {import('../server/page/types').SerializedHttpError} */ (error)
+					error: /** @type {import('../server/page/types').SerializedHttpError} */ (original_error)
 						?.__is_http_error
 						? new HttpError(
-								/** @type {import('../server/page/types').SerializedHttpError} */ (error).status,
-								error.message
+								/** @type {import('../server/page/types').SerializedHttpError} */ (
+									original_error
+								).status,
+								original_error.message
 						  )
-						: error,
+						: original_error,
 					validation_errors,
 					routeId
 				});
diff --git a/packages/kit/src/runtime/client/types.d.ts b/packages/kit/src/runtime/client/types.d.ts
index af191e77176f..5c9757b17ad5 100644
--- a/packages/kit/src/runtime/client/types.d.ts
+++ b/packages/kit/src/runtime/client/types.d.ts
@@ -28,7 +28,7 @@ export interface Client {
 		params: Record<string, string>;
 		routeId: string | null;
 		data: Array<import('types').ServerDataNode | import('types').ServerErrorNode | null>;
-		errors: Record<string, any>;
+		errors: Record<string, any> | null;
 	}) => Promise<void>;
 	_start_router: () => void;
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 540d46a08b15..f4825e365c0e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -278,7 +278,7 @@ importers:
       '@types/sade': ^1.7.4
       '@types/set-cookie-parser': ^2.4.2
       cookie: ^0.5.0
-      devalue: ^3.1.0
+      devalue: ^3.1.1
       kleur: ^4.1.4
       magic-string: ^0.26.2
       marked: ^4.0.16
@@ -298,7 +298,7 @@ importers:
     dependencies:
       '@sveltejs/vite-plugin-svelte': 1.0.1_svelte@3.48.0+vite@3.0.9
       cookie: 0.5.0
-      devalue: 3.1.0
+      devalue: 3.1.1
       kleur: 4.1.5
       magic-string: 0.26.2
       mime: 3.0.0
@@ -1748,8 +1748,8 @@ packages:
     resolution: {integrity: sha512-463v3ZeIrcWtdgIg6vI6XUncguvr2TnGl4SzDXinkt9mSLpBJKXT3mW6xT3VQdDN11+WVs29pgvivTc4Lp8v+w==}
     engines: {node: '>=8'}
 
-  /devalue/3.1.0:
-    resolution: {integrity: sha512-5Nb73BzNSGvDJNWCVXHv9R+rhNg0pN+OsgeJ/BRYCvMsEBCDfP9Ci/5cHjSPoOSMWBrh3MtUDQtChfdKYWLxeg==}
+  /devalue/3.1.1:
+    resolution: {integrity: sha512-rq3zudzCv66+Kmt1iIVtdSl/czOhGsWrmgFuilyVCIZLHdK9n9Fg89YU+DPrhD9ZQBH+wAT6gIZPPS9wC7HV1w==}
     dev: false
 
   /diff/5.1.0:

From 60c8d6620f81a6dc89abb422af549dc7201212c6 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 14:50:39 -0400
Subject: [PATCH 12/23] fix

---
 packages/kit/package.json                | 2 +-
 packages/kit/src/runtime/server/utils.js | 2 +-
 pnpm-lock.yaml                           | 8 ++++----
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/kit/package.json b/packages/kit/package.json
index 5b2d59a246a0..c276489c229d 100644
--- a/packages/kit/package.json
+++ b/packages/kit/package.json
@@ -12,7 +12,7 @@
 	"dependencies": {
 		"@sveltejs/vite-plugin-svelte": "^1.0.1",
 		"cookie": "^0.5.0",
-		"devalue": "^3.1.1",
+		"devalue": "^3.1.2",
 		"kleur": "^4.1.4",
 		"magic-string": "^0.26.2",
 		"mime": "^3.0.0",
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index 2c2b7a399ced..1f0382ca8f19 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -125,7 +125,7 @@ export function data_response(data) {
 			}
 		});
 	} catch (e) {
-		return new Response(`throw new Error(${JSON.stringify(e.message)})`, {
+		return new Response(`throw new Error(${JSON.stringify(/** @type {any} */ (e).message)})`, {
 			headers: {
 				'content-type': 'application/javascript'
 			}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index f4825e365c0e..45616a3e91a5 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -278,7 +278,7 @@ importers:
       '@types/sade': ^1.7.4
       '@types/set-cookie-parser': ^2.4.2
       cookie: ^0.5.0
-      devalue: ^3.1.1
+      devalue: ^3.1.2
       kleur: ^4.1.4
       magic-string: ^0.26.2
       marked: ^4.0.16
@@ -298,7 +298,7 @@ importers:
     dependencies:
       '@sveltejs/vite-plugin-svelte': 1.0.1_svelte@3.48.0+vite@3.0.9
       cookie: 0.5.0
-      devalue: 3.1.1
+      devalue: 3.1.2
       kleur: 4.1.5
       magic-string: 0.26.2
       mime: 3.0.0
@@ -1748,8 +1748,8 @@ packages:
     resolution: {integrity: sha512-463v3ZeIrcWtdgIg6vI6XUncguvr2TnGl4SzDXinkt9mSLpBJKXT3mW6xT3VQdDN11+WVs29pgvivTc4Lp8v+w==}
     engines: {node: '>=8'}
 
-  /devalue/3.1.1:
-    resolution: {integrity: sha512-rq3zudzCv66+Kmt1iIVtdSl/czOhGsWrmgFuilyVCIZLHdK9n9Fg89YU+DPrhD9ZQBH+wAT6gIZPPS9wC7HV1w==}
+  /devalue/3.1.2:
+    resolution: {integrity: sha512-wUXbMGPAsBx79UF14nsWSsJlC7RcwPlf2w3bGheODWxKx57e9n68ceoijbqCJCEbjyo0S79nqfPwQgyijwLaqw==}
     dev: false
 
   /diff/5.1.0:

From 859f4cbd0d3028f482e782f160b68ce44a6ddb8e Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 15:09:32 -0400
Subject: [PATCH 13/23] fix

---
 packages/kit/src/runtime/server/index.js           | 2 +-
 packages/kit/test/prerendering/basics/test/test.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/kit/src/runtime/server/index.js b/packages/kit/src/runtime/server/index.js
index c87cf264a73e..5c03fb045901 100644
--- a/packages/kit/src/runtime/server/index.js
+++ b/packages/kit/src/runtime/server/index.js
@@ -83,7 +83,7 @@ export async function respond(request, options, state) {
 		}
 	}
 
-	if (route?.page) {
+	if (route?.page && !is_data_request) {
 		const normalized = normalize_path(url.pathname, options.trailing_slash);
 
 		if (normalized !== url.pathname && !state.prerendering?.fallback) {
diff --git a/packages/kit/test/prerendering/basics/test/test.js b/packages/kit/test/prerendering/basics/test/test.js
index 32d09321a2e2..29a62b3cebe0 100644
--- a/packages/kit/test/prerendering/basics/test/test.js
+++ b/packages/kit/test/prerendering/basics/test/test.js
@@ -27,7 +27,7 @@ test('renders a server-side redirect', () => {
 
 	const code = read('redirect-server/__data.js');
 	const window = {};
-	new Function('window', `(${code})`)(window);
+	new Function('window', code)(window);
 
 	assert.equal(window.__sveltekit_data, {
 		type: 'redirect',

From 5a113b61f460049f425232639fa076385eebc1a4 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 15:17:07 -0400
Subject: [PATCH 14/23] update docs

---
 documentation/docs/03-routing.md | 2 +-
 documentation/docs/05-load.md    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/documentation/docs/03-routing.md b/documentation/docs/03-routing.md
index b085b4f9ac0f..5dff407cc72e 100644
--- a/documentation/docs/03-routing.md
+++ b/documentation/docs/03-routing.md
@@ -106,7 +106,7 @@ export async function load({ params }) {
 }
 ```
 
-During client-side navigation, SvelteKit will load this data using `fetch`, which means that the returned value must be serializable as JSON.
+During client-side navigation, SvelteKit will load this data from the server, which means that the returned value must be serializable using [devalue](https://github.com/rich-harris/devalue).
 
 #### Actions
 
diff --git a/documentation/docs/05-load.md b/documentation/docs/05-load.md
index 040eaaf3c9a3..14f185a3519c 100644
--- a/documentation/docs/05-load.md
+++ b/documentation/docs/05-load.md
@@ -4,7 +4,7 @@ title: Loading data
 
 A [`+page.svelte`](/docs/routing#page-page-svelte) or [`+layout.svelte`](/docs/routing#layout-layout-svelte) gets its `data` from a `load` function.
 
-If the `load` function is defined in `+page.js` or `+layout.js` it will run both on the server and in the browser. If it's instead defined in `+page.server.js` or `+layout.server.js` it will only run on the server, in which case it can (for example) make database calls and access private [environment variables](/docs/modules#$env-static-private), but can only return data that can be serialized as JSON.
+If the `load` function is defined in `+page.js` or `+layout.js` it will run both on the server and in the browser. If it's instead defined in `+page.server.js` or `+layout.server.js` it will only run on the server, in which case it can (for example) make database calls and access private [environment variables](/docs/modules#$env-static-private), but can only return data that can be serialized with [devalue](https://github.com/rich-harris/devalue).
 
 ```js
 /// file: src/routes/+page.js

From 74d595b37853e7cbba8ec1f4f7596361f4af6106 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 15:46:21 -0400
Subject: [PATCH 15/23] fix

---
 packages/kit/test/apps/options/test/test.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/kit/test/apps/options/test/test.js b/packages/kit/test/apps/options/test/test.js
index 61cef9a29256..f3e17419a3ac 100644
--- a/packages/kit/test/apps/options/test/test.js
+++ b/packages/kit/test/apps/options/test/test.js
@@ -188,7 +188,7 @@ test.describe('trailingSlash', () => {
 
 		/** @type {string[]} */
 		let requests = [];
-		page.on('request', (r) => requests.push(r.url()));
+		page.on('request', (r) => requests.push(new URL(r.url()).pathname));
 
 		// also wait for network processing to complete, see
 		// https://playwright.dev/docs/network#network-events
@@ -201,7 +201,7 @@ test.describe('trailingSlash', () => {
 			expect(requests.filter((req) => req.endsWith('.js')).length).toBeGreaterThan(0);
 		}
 
-		expect(requests.includes(`${baseURL}/path-base/prefetching/prefetched/__data.js`)).toBe(true);
+		expect(requests.includes(`/path-base/prefetching/prefetched/__data.js`)).toBe(true);
 
 		requests = [];
 		await app.goto('/path-base/prefetching/prefetched');

From 91115f6e6519190224ac6285c315fab3bddcec04 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Fri, 26 Aug 2022 16:04:55 -0400
Subject: [PATCH 16/23] changeset

---
 .changeset/tender-spiders-fail.md | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 .changeset/tender-spiders-fail.md

diff --git a/.changeset/tender-spiders-fail.md b/.changeset/tender-spiders-fail.md
new file mode 100644
index 000000000000..2630783d2465
--- /dev/null
+++ b/.changeset/tender-spiders-fail.md
@@ -0,0 +1,7 @@
+---
+'@sveltejs/adapter-netlify': patch
+'@sveltejs/adapter-vercel': patch
+'@sveltejs/kit': patch
+---
+
+Use devalue to serialize server-only `load` return values

From 5b4afb5bf2898be4cb7d62cc611c16f04233060f Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Sat, 27 Aug 2022 07:37:12 -0400
Subject: [PATCH 17/23] fix

---
 packages/kit/src/runtime/client/client.js | 11 +++++++----
 packages/kit/src/runtime/server/utils.js  |  5 ++++-
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index ba81b3922940..66a36f53a98a 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -701,10 +701,13 @@ export function create_client({ target, base, trailing_slash }) {
 		if (route.uses_server_data && invalid_server_nodes.some(Boolean)) {
 			try {
 				server_data = await load_data(url, invalid_server_nodes);
-			} catch (e) {
-				// something went catastrophically wrong — bail and defer to the server
-				native_navigation(url);
-				return;
+			} catch (error) {
+				return load_root_error_page({
+					status: 500,
+					error: /** @type {Error} */ (error),
+					url,
+					routeId: route.id
+				});
 			}
 
 			if (server_data.type === 'redirect') {
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index 1f0382ca8f19..09b36614ebc9 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -125,7 +125,10 @@ export function data_response(data) {
 			}
 		});
 	} catch (e) {
-		return new Response(`throw new Error(${JSON.stringify(/** @type {any} */ (e).message)})`, {
+		const error = /** @type {any} */ (e);
+		const match = /\[(\d+)\]\.data\.(.+)/.exec(error.path);
+		const message = match ? `${error.message} (data.${match[2]})` : error.message;
+		return new Response(`throw new Error(${JSON.stringify(message)})`, {
 			headers: {
 				'content-type': 'application/javascript'
 			}

From ae423fd9abba9f6c04f0e718405b6f82b00f03aa Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Sun, 28 Aug 2022 11:59:20 -0400
Subject: [PATCH 18/23] comment

---
 packages/kit/src/runtime/client/client.js | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 66a36f53a98a..22f991a3f52b 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -1368,6 +1368,13 @@ async function load_data(url, invalid) {
 	data_url.searchParams.set('__invalid', invalid.map((x) => (x ? 'y' : 'n')).join(''));
 	data_url.searchParams.set('__id', String(data_id++));
 
+	// The __data.js file is generated by the server and looks like
+	// `window.__sveltekit_data = ${devalue(data)}`. We do this instead
+	// of `export const data` because modules are cached indefinitely,
+	// and that would cause memory leaks.
+	//
+	// The data is read and deleted in the same tick as the promise
+	// resolves, so it's not vulnerable to race conditions
 	await import(/* @vite-ignore */ data_url.href);
 
 	// @ts-expect-error

From 3e3d05de1468f6541154c7f284d49649016d7041 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Sun, 28 Aug 2022 12:01:15 -0400
Subject: [PATCH 19/23] add comments

---
 packages/kit/src/runtime/server/page/render.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
index a2574aeaf879..565365659ad2 100644
--- a/packages/kit/src/runtime/server/page/render.js
+++ b/packages/kit/src/runtime/server/page/render.js
@@ -179,6 +179,7 @@ export async function render_response({
 	try {
 		serialized.data = devalue(branch.map(({ server_data }) => server_data));
 	} catch (e) {
+		// If we're here, the data could not be serialized with devalue
 		// TODO if we wanted to get super fancy we could track down the origin of the `load`
 		// function, but it would mean passing more stuff around than we currently do
 		const error = /** @type {any} */ (e);
@@ -191,6 +192,7 @@ export async function render_response({
 		try {
 			serialized.errors = devalue(validation_errors);
 		} catch (e) {
+			// If we're here, the data could not be serialized with devalue
 			const error = /** @type {any} */ (e);
 			if (error.path) throw new Error(`${error.message} (errors.${error.path})`);
 			throw error;

From b970d5cfafd076d943b8e8ce3eb1d42f9cc490ab Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Sun, 28 Aug 2022 12:01:27 -0400
Subject: [PATCH 20/23] use already-serialized data

---
 packages/kit/src/runtime/server/page/render.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
index 565365659ad2..9ed1d1e647a1 100644
--- a/packages/kit/src/runtime/server/page/render.js
+++ b/packages/kit/src/runtime/server/page/render.js
@@ -217,8 +217,8 @@ export async function render_response({
 				node_ids: [${branch.map(({ node }) => node.index).join(', ')}],
 				params: ${devalue(event.params)},
 				routeId: ${s(event.routeId)},
-				data: ${devalue(branch.map(({ server_data }) => server_data))},
-				errors: ${validation_errors ? devalue(validation_errors) : 'null'}
+				data: ${serialized.data},
+				errors: ${serialized.errors}
 			}` : 'null'}
 		});
 	`;

From 358d0ceb323f9c53a2bfc6ef1acd9f742eadf1b5 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Sun, 28 Aug 2022 12:04:36 -0400
Subject: [PATCH 21/23] use DATA_SUFFIX constant

---
 packages/kit/src/runtime/client/client.js     | 3 ++-
 packages/kit/src/runtime/server/page/index.js | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 22f991a3f52b..2c44348eaa71 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -10,6 +10,7 @@ import Root from '__GENERATED__/root.svelte';
 import { nodes, dictionary, matchers } from '__GENERATED__/client-manifest.js';
 import { HttpError, Redirect } from '../control.js';
 import { stores } from './singletons.js';
+import { DATA_SUFFIX } from '../../constants.js';
 
 const SCROLL_KEY = 'sveltekit:scroll';
 const INDEX_KEY = 'sveltekit:index';
@@ -1364,7 +1365,7 @@ let data_id = 1;
  */
 async function load_data(url, invalid) {
 	const data_url = new URL(url);
-	data_url.pathname += `${url.pathname.endsWith('/') ? '' : '/'}__data.js`;
+	data_url.pathname = url.pathname.replace(/\/$/, '') + DATA_SUFFIX;
 	data_url.searchParams.set('__invalid', invalid.map((x) => (x ? 'y' : 'n')).join(''));
 	data_url.searchParams.set('__id', String(data_id++));
 
diff --git a/packages/kit/src/runtime/server/page/index.js b/packages/kit/src/runtime/server/page/index.js
index e29b5eb6e8cc..d350441a7158 100644
--- a/packages/kit/src/runtime/server/page/index.js
+++ b/packages/kit/src/runtime/server/page/index.js
@@ -9,6 +9,7 @@ import { error, json } from '../../../exports/index.js';
 import { compact } from '../../../utils/array.js';
 import { normalize_error } from '../../../utils/error.js';
 import { load_data, load_server_data } from './load_data.js';
+import { DATA_SUFFIX } from '../../../constants.js';
 
 /**
  * @typedef {import('./types.js').Loaded} Loaded
@@ -103,7 +104,7 @@ export async function render_page(event, route, page, options, state, resolve_op
 		}
 
 		const should_prerender_data = nodes.some((node) => node?.server);
-		const data_pathname = `${event.url.pathname.replace(/\/$/, '')}/__data.js`;
+		const data_pathname = event.url.pathname.replace(/\/$/, '') + DATA_SUFFIX;
 
 		// it's crucial that we do this before returning the non-SSR response, otherwise
 		// SvelteKit will erroneously believe that the path has been prerendered,

From b0bea0131eefbf1cc074014d53f628b3f1c26b8a Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Mon, 29 Aug 2022 10:47:33 -0400
Subject: [PATCH 22/23] error nodes are not serialized for hydration

---
 packages/kit/src/runtime/client/client.js  | 8 --------
 packages/kit/src/runtime/client/types.d.ts | 2 +-
 2 files changed, 1 insertion(+), 9 deletions(-)

diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index 2c44348eaa71..db1ec271ade2 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -1292,14 +1292,6 @@ export function create_client({ target, base, trailing_slash }) {
 				const branch_promises = node_ids.map(async (n, i) => {
 					const server_data_node = server_data_nodes[i];
 
-					if (server_data_node?.type === 'error') {
-						if (server_data_node.httperror) {
-							throw error(server_data_node.httperror.status, server_data_node.httperror.message);
-						}
-
-						throw server_data_node.error;
-					}
-
 					return load_node({
 						loader: nodes[n],
 						url,
diff --git a/packages/kit/src/runtime/client/types.d.ts b/packages/kit/src/runtime/client/types.d.ts
index 5c9757b17ad5..e86bc3ae0eb2 100644
--- a/packages/kit/src/runtime/client/types.d.ts
+++ b/packages/kit/src/runtime/client/types.d.ts
@@ -27,7 +27,7 @@ export interface Client {
 		node_ids: number[];
 		params: Record<string, string>;
 		routeId: string | null;
-		data: Array<import('types').ServerDataNode | import('types').ServerErrorNode | null>;
+		data: Array<import('types').ServerDataNode | null>;
 		errors: Record<string, any> | null;
 	}) => Promise<void>;
 	_start_router: () => void;

From 5eafe2c0cc9b8ff8622d1ba16a119ae3b3dc2c9e Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Mon, 29 Aug 2022 10:49:41 -0400
Subject: [PATCH 23/23] fix

---
 packages/kit/src/runtime/client/start.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/kit/src/runtime/client/start.js b/packages/kit/src/runtime/client/start.js
index 78c245841616..aeadbc23d40f 100644
--- a/packages/kit/src/runtime/client/start.js
+++ b/packages/kit/src/runtime/client/start.js
@@ -20,7 +20,7 @@ export { set_public_env } from '../env-public.js';
  *     node_ids: number[];
  *     params: Record<string, string>;
  *     routeId: string | null;
- *     data: Array<import('types').ServerDataNode | import('types').ServerErrorNode | null>;
+ *     data: Array<import('types').ServerDataNode | null>;
  *     errors: Record<string, any> | null;
  *   };
  * }} opts