print warnings in dev mode for unused data

* add --build and --build-dir options to sapper export (#325)

* tweak export logging, update port-authority to prevent timeout bug

* better logging of export progress

* handle case where linked resource is already fetched

* default to .sapper/dev instead of .sapper

* handle query params and redirects

* dont write server_info.json either - second half of #318

* update changelog

* update lockfile

* try to track down ci test failures

* err wut

* curiouser and curiouser

* ok, seems to work now

CHANGELOG.md

@@ -1,5 +1,28 @@
 # sapper changelog
 
+## 0.15.5
+
+* Faster `export` with more explanatory output ([#335](https://github.com/sveltejs/sapper/pull/335))
+* Only blur `activeElement` if it exists ([#332](https://github.com/sveltejs/sapper/issues/332))
+* Don't emit `client_info.json` or `server_info.json` ([#318](https://github.com/sveltejs/sapper/issues/318))
+
+## 0.15.4
+
+* Add `ignore` option ([#326](https://github.com/sveltejs/sapper/pull/326))
+
+## 0.15.3
+
+* Crawl pages in parallel when exporting ([#329](https://github.com/sveltejs/sapper/pull/329))
+* Don't minify inline JS when exporting ([#328](https://github.com/sveltejs/sapper/pull/328))
+
+## 0.15.2
+
+* Collapse component chains where no intermediate layout component is specified ([#312](https://github.com/sveltejs/sapper/issues/312))
+
+## 0.15.1
+
+* Prevent confusing error when no root layout is specified
+
 ## 0.15.0
 
 * Nested routes (consult [migration guide](https://sapper.svelte.technology/guide#0-14-to-0-15) and docs on [layouts](https://sapper.svelte.technology/guide#layouts)) ([#262](https://github.com/sveltejs/sapper/issues/262))

README.md

@@ -31,6 +31,44 @@ npm run build
 npm start
 ```
 
+## Development
+
+Pull requests are encouraged and always welcome. [Pick an issue](https://github.com/sveltejs/sapper/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc) and help us out!
+
+To install and work on Sapper locally:
+
+```bash
+git clone git@github.com:sveltejs/sapper.git
+cd sapper
+npm install
+npm run dev
+```
+
+### Linking to a Live Project
+
+You can make changes locally to Sapper and test it against a local Sapper project. For a quick project that takes almost no setup, use the default [sapper-template](https://github.com/sveltejs/sapper-template) project. Instruction on setup are found in that project repository.
+
+To link Sapper to your project, from the root of your local Sapper git checkout:
+
+```bash
+cd sapper
+npm link
+```
+
+Then, to link from `sapper-template` (or any other given project):
+
+```bash
+cd sapper-template
+npm link sapper
+```
+
+You should be good to test changes locally.
+
+### Running Tests
+
+```bash
+npm run test
+```
 
 ## License
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "sapper",
-  "version": "0.15.0",
+  "version": "0.15.4",
   "description": "Military-grade apps, engineered by Svelte",
   "main": "dist/middleware.ts.js",
   "bin": {
@@ -23,12 +23,12 @@
     "cheerio": "^1.0.0-rc.2",
     "chokidar": "^2.0.3",
     "cookie": "^0.3.1",
-    "devalue": "^1.0.1",
+    "devalue": "^1.0.4",
     "glob": "^7.1.2",
     "html-minifier": "^3.5.16",
     "mkdirp": "^0.5.1",
     "node-fetch": "^2.1.1",
-    "port-authority": "^1.0.2",
+    "port-authority": "^1.0.5",
     "pretty-bytes": "^5.0.0",
     "pretty-ms": "^3.1.0",
     "require-relative": "^0.8.7",

src/api/build.ts

@@ -4,8 +4,7 @@ import mkdirp from 'mkdirp';
 import rimraf from 'rimraf';
 import { EventEmitter } from 'events';
 import { minify_html } from './utils/minify_html';
-import { create_compilers, create_main_manifests, create_routes, create_serviceworker_manifest } from '../core'
+import { create_compilers, create_main_manifests, create_routes, create_serviceworker_manifest } from '../core';
-import { locations } from '../config';
 import * as events from './interfaces';
 
 export function build(opts: {}) {
@@ -62,7 +61,6 @@ async function execute(emitter: EventEmitter, {
 	});
 
 	const client_info = client_stats.toJson();
-	fs.writeFileSync(path.join(dest, 'client_info.json'), JSON.stringify(client_info));
 	fs.writeFileSync(path.join(dest, 'client_assets.json'), JSON.stringify(client_info.assetsByChunkName));
 
 	const server_stats = await compile(server);

src/api/dev.ts

@@ -9,6 +9,7 @@ import format_messages from 'webpack-format-messages';
 import { locations } from '../config';
 import { EventEmitter } from 'events';
 import { create_routes, create_main_manifests, create_compilers, create_serviceworker_manifest } from '../core';
+import Deferred from './utils/Deferred';
 import * as events from './interfaces';
 
 export function dev(opts) {
@@ -168,8 +169,6 @@ class Watcher extends EventEmitter {
 			},
 
 			result: info => {
-				fs.writeFileSync(path.join(dest, 'server_info.json'), JSON.stringify(info, null, '  '));
-
 				this.deferreds.client.promise.then(() => {
 					const restart = () => {
 						log = '';
@@ -225,11 +224,8 @@ class Watcher extends EventEmitter {
 					});
 
 					this.proc.on('message', message => {
-						if (message.__sapper__ && message.event === 'basepath') {
+						if (!message.__sapper__) return;
-							this.emit('basepath', {
+						this.emit(message.event, message);
-								basepath: message.basepath
-							});
-						}
 					});
 
 					this.proc.on('exit', emitFatal);
@@ -252,7 +248,6 @@ class Watcher extends EventEmitter {
 			},
 
 			result: info => {
-				fs.writeFileSync(path.join(dest, 'client_info.json'), JSON.stringify(info));
 				fs.writeFileSync(path.join(dest, 'client_assets.json'), JSON.stringify(info.assetsByChunkName, null, '  '));
 				this.deferreds.client.fulfil();
 
@@ -401,19 +396,6 @@ function mungeWebpackError(message: string, duplicate: boolean) {
 	};
 }
 
-class Deferred {
-	promise: Promise<any>;
-	fulfil: (value?: any) => void;
-	reject: (error: Error) => void;
-
-	constructor() {
-		this.promise = new Promise((fulfil, reject) => {
-			this.fulfil = fulfil;
-			this.reject = reject;
-		});
-	}
-}
-
 const INTERVAL = 10000;
 
 class DevServer {

src/api/export.ts

@@ -7,7 +7,7 @@ import fetch from 'node-fetch';
 import * as ports from 'port-authority';
 import { EventEmitter } from 'events';
 import { minify_html } from './utils/minify_html';
-import { locations } from '../config';
+import Deferred from './utils/Deferred';
 import * as events from './interfaces';
 
 export function exporter(opts: {}) {
@@ -52,6 +52,10 @@ async function execute(emitter: EventEmitter, {
 
 	const origin = `http://localhost:${port}`;
 
+	emitter.emit('info', {
+		message: `Crawling ${origin}`
+	});
+
 	const proc = child_process.fork(path.resolve(`${build}/server.js`), [], {
 		cwd: process.cwd(),
 		env: Object.assign({
@@ -64,11 +68,21 @@ async function execute(emitter: EventEmitter, {
 
 	const seen = new Set();
 	const saved = new Set();
+	const deferreds = new Map();
+
+	function get_deferred(pathname: string) {
+		if (!deferreds.has(pathname)) {
+			deferreds.set(pathname, new Deferred())	;
+		}
+
+		return deferreds.get(pathname);
+	}
 
 	proc.on('message', message => {
 		if (!message.__sapper__ || message.event !== 'file') return;
 
-		let file = new URL(message.url, origin).pathname.slice(1);
+		const pathname = new URL(message.url, origin).pathname;
+		let file = pathname.slice(1);
 		let { body } = message;
 
 		if (saved.has(file)) return;
@@ -83,24 +97,26 @@ async function execute(emitter: EventEmitter, {
 
 		emitter.emit('file', <events.FileEvent>{
 			file,
-			size: body.length
+			size: body.length,
+			status: message.status
 		});
 
 		sander.writeFileSync(export_dir, file, body);
+
+		get_deferred(pathname).fulfil();
 	});
 
 	async function handle(url: URL) {
+		const pathname = url.pathname || '/';
+
+		if (seen.has(pathname)) return;
+		seen.add(pathname);
+
+		const deferred = get_deferred(pathname);
+
 		const r = await fetch(url.href);
 		const range = ~~(r.status / 100);
 
-		if (range >= 4) {
-			emitter.emit('failure', <events.FailureEvent>{
-				status: r.status,
-				pathname: url.pathname
-			});
-			return;
-		}
-
 		if (range === 2) {
 			if (r.headers.get('Content-Type') === 'text/html') {
 				const body = await r.text();
@@ -111,18 +127,14 @@ async function execute(emitter: EventEmitter, {
 
 				$('a[href]').each((i: number, $a) => {
 					const url = new URL($a.attribs.href, base.href);
-
+					if (url.origin === origin) urls.push(url);
-					if (url.origin === origin && !seen.has(url.pathname)) {
-						seen.add(url.pathname);
-						urls.push(url);
-					}
 				});
 
-				for (const url of urls) {
+				await Promise.all(urls.map(handle));
-					await handle(url);
-				}
 			}
 		}
+
+		await deferred.promise;
 	}
 
 	return ports.wait(port)

src/api/utils/Deferred.ts

@@ -0,0 +1,12 @@
+export default class Deferred {
+	promise: Promise<any>;
+	fulfil: (value?: any) => void;
+	reject: (error: Error) => void;
+
+	constructor() {
+		this.promise = new Promise((fulfil, reject) => {
+			this.fulfil = fulfil;
+			this.reject = reject;
+		});
+	}
+}

src/api/utils/minify_html.ts

@@ -8,7 +8,7 @@ export function minify_html(html: string) {
 		decodeEntities: true,
 		html5: true,
 		minifyCSS: true,
-		minifyJS: true,
+		minifyJS: false,
 		removeAttributeQuotes: true,
 		removeComments: true,
 		removeOptionalTags: true,

src/cli.ts

@@ -1,11 +1,8 @@
 import * as fs from 'fs';
 import * as path from 'path';
-import * as child_process from 'child_process';
 import sade from 'sade';
 import * as colors from 'ansi-colors';
 import prettyMs from 'pretty-ms';
-// import upgrade from './cli/upgrade';
-import * as ports from 'port-authority';
 import * as pkg from '../package.json';
 
 const prog = sade('sapper').version(pkg.version);
@@ -65,19 +62,22 @@ prog.command('start [dir]')
 
 prog.command('export [dest]')
 	.describe('Export your app as static files (if possible)')
+	.option('--build', '(Re)build app before exporting', true)
+	.option('--build-dir', 'Specify a custom temporary build directory', '.sapper/prod')
 	.option('--basepath', 'Specify a base path')
-	.action(async (dest = 'export', opts: { basepath?: string }) => {
+	.action(async (dest = 'export', opts: { build: boolean, 'build-dir': string, basepath?: string }) => {
-		console.log(`> Building...`);
-
 		process.env.NODE_ENV = 'production';
-		process.env.SAPPER_DEST = '.sapper/.export';
+		process.env.SAPPER_DEST = opts['build-dir'];
 
 		const start = Date.now();
 
 		try {
+			if (opts.build) {
+				console.log(`> Building...`);
 				const { build } = await import('./cli/build');
 				await build();
-			console.error(`\n> Built in ${elapsed(start)}. Crawling site...`);
+				console.error(`\n> Built in ${elapsed(start)}`);
+			}
 
 			const { exporter } = await import('./cli/export');
 			await exporter(dest, opts);

src/cli/dev.ts

@@ -2,6 +2,7 @@ import * as path from 'path';
 import * as colors from 'ansi-colors';
 import * as child_process from 'child_process';
 import prettyMs from 'pretty-ms';
+import pb from 'pretty-bytes';
 import { dev as _dev } from '../api/dev';
 import * as events from '../api/interfaces';
 
@@ -44,6 +45,32 @@ export function dev(opts: { port: number, open: boolean }) {
 			if (event.log) console.log(event.log);
 		});
 
+		watcher.on('preload', (event) => {
+			if (event.size > 25000) {
+				console.log(colors.bold.yellow(`${event.url} — large amount of preloaded data`));
+				console.log(`${colors.bold(pb(event.size))} of data was preloaded in total, above the recommended limit of ${pb(25000)}`);
+			}
+		});
+
+		watcher.on('unused_data', (event) => {
+			console.log(colors.bold.yellow(`${event.url} — unused preloaded data`));
+			console.log(`More data was returned from \`preload\` than was used during the initial render. Consider only returning essential data.`);
+
+			event.discrepancies.forEach(discrepancy => {
+				console.log(`${colors.bold(discrepancy.file)} loaded ${colors.bold(pb(discrepancy.preloaded))}, of which ${discrepancy.rendered > 2 ? `only ${colors.bold(pb(discrepancy.rendered))}` : 'none'} was used. The following properties were not referenced:`);
+
+				const slice = discrepancy.props.length > 12
+					? discrepancy.props.slice(0, 10)
+					: discrepancy.props;
+
+				console.log(slice.map((prop: string) => `• ${prop}`).join('\n'));
+
+				if (discrepancy.props.length > slice.length) {
+					console.log(`...and ${discrepancy.props.length - slice.length} more`);
+				}
+			});
+		});
+
 		watcher.on('build', (event: events.BuildEvent) => {
 			if (event.errors.length) {
 				console.log(`${colors.bold.red(`✗ ${event.type}`)}`);

src/cli/export.ts

@@ -3,6 +3,11 @@ import * as colors from 'ansi-colors';
 import prettyBytes from 'pretty-bytes';
 import { locations } from '../config';
 
+function left_pad(str: string, len: number) {
+	while (str.length < len) str = ` ${str}`;
+	return str;
+}
+
 export function exporter(export_dir: string, { basepath = '' }) {
 	return new Promise((fulfil, reject) => {
 		try {
@@ -13,11 +18,19 @@ export function exporter(export_dir: string, { basepath = '' }) {
 			});
 
 			emitter.on('file', event => {
-				console.log(`${colors.bold.cyan(event.file)} ${colors.gray(`(${prettyBytes(event.size)})`)}`);
+				const pb = prettyBytes(event.size);
+				const size_color = event.size > 150000 ? colors.bold.red : event.size > 50000 ? colors.bold.yellow : colors.bold.gray;
+				const size_label = size_color(left_pad(prettyBytes(event.size), 10));
+
+				const file_label = event.status === 200
+					? event.file
+					: colors.bold[event.status >= 400 ? 'red' : 'yellow'](`(${event.status}) ${event.file}`);
+
+				console.log(`${size_label}   ${file_label}`);
 			});
 
-			emitter.on('failure', event => {
+			emitter.on('info', event => {
-				console.log(`${colors.red(`> Received ${event.status} response when fetching ${event.pathname}`)}`);
+				console.log(colors.bold.cyan(`> ${event.message}`));
 			});
 
 			emitter.on('error', event => {

src/config.ts

@@ -6,5 +6,5 @@ export const locations = {
 	base:   () => path.resolve(process.env.SAPPER_BASE || ''),
 	app:    () => path.resolve(process.env.SAPPER_BASE || '', process.env.SAPPER_APP    || 'app'),
 	routes: () => path.resolve(process.env.SAPPER_BASE || '', process.env.SAPPER_ROUTES || 'routes'),
-	dest:   () => path.resolve(process.env.SAPPER_BASE || '', process.env.SAPPER_DEST   || '.sapper')
+	dest:   () => path.resolve(process.env.SAPPER_BASE || '', process.env.SAPPER_DEST   || `.sapper/${dev() ? 'dev' : 'prod'}`)
 };

src/core/create_manifests.ts

@@ -62,7 +62,7 @@ function generate_client(
 
 	let code = `
 		// This file is generated by Sapper — do not edit it!
-		import root from '${posixify(`${path_to_routes}/${routes.root.file}`)}';
+		import root from '${get_file(path_to_routes, routes.root)}';
 		import error from '${posixify(`${path_to_routes}/_error.html`)}';
 
 		${routes.components.map(component =>
@@ -79,6 +79,8 @@ function generate_client(
 					pattern: ${page.pattern},
 					parts: [
 						${page.parts.map(part => {
+							if (part === null) return 'null';
+
 							if (part.params.length > 0) {
 								const props = part.params.map((param, i) => `${param}: match[${i + 1}]`);
 								return `{ component: ${part.component.name}, params: match => ({ ${props.join(', ')} }) }`;
@@ -124,7 +126,7 @@ function generate_server(
 			`import * as ${route.name} from '${posixify(`${path_to_routes}/${route.file}`)}';`),
 		routes.components.map(component =>
 			`import ${component.name} from '${get_file(path_to_routes, component)}';`),
-		`import root from '${posixify(`${path_to_routes}/${routes.root.file}`)}';`,
+		`import root from '${get_file(path_to_routes, routes.root)}';`,
 		`import error from '${posixify(`${path_to_routes}/_error.html`)}';`
 	);
 
@@ -150,8 +152,11 @@ function generate_server(
 					pattern: ${page.pattern},
 					parts: [
 						${page.parts.map(part => {
+							if (part === null) return 'null';
+
 							const props = [
 								`name: "${part.component.name}"`,
+								`file: "${part.component.file}"`,
 								`component: ${part.component.name}`
 							];
 

src/core/create_routes.ts

@@ -101,27 +101,21 @@ export default function create_routes(cwd = locations.routes()) {
 
 			if (item.is_dir) {
 				const index = path.join(dir, item.basename, '_layout.html');
-				const layout = fs.existsSync(index)
+
-					? {
+				const component = fs.existsSync(index) && {
 					name: `${get_slug(item.file)}__layout`,
 					file: `${item.file}/_layout.html`
-					}
+				};
-					: null;
 
-				if (layout) {
+				if (component) components.push(component);
-					components.push(layout);
-				} else if (components.indexOf(default_layout) === -1) {
-					components.push(default_layout);
-				}
 
 				walk(
 					path.join(dir, item.basename),
 					segments,
 					params,
-					stack.concat({
+					component
-						component: layout || default_layout,
+						? stack.concat({ component, params })
-						params
+						: stack.concat(null)
-					})
 				);
 			}
 

src/middleware.ts

@@ -8,6 +8,9 @@ import fetch from 'node-fetch';
 import { lookup } from './middleware/mime';
 import { locations, dev } from './config';
 import sourceMapSupport from 'source-map-support';
+import prettyBytes from 'pretty-bytes';
+import { wrap_data } from './middleware/wrap_data';
+import { list_unused_properties } from './middleware/list_unused_properties';
 
 sourceMapSupport.install();
 
@@ -73,9 +76,18 @@ interface Component {
 	preload: (data: any) => any | Promise<any>
 }
 
+const IGNORE = '__SAPPER__IGNORE__';
+function toIgnore(uri: string, val: any) {
+	if (Array.isArray(val)) return val.some(x => toIgnore(uri, x));
+	if (val instanceof RegExp) return val.test(uri);
+	if (typeof val === 'function') return val(uri);
+	return uri.startsWith(val.charCodeAt(0) === 47 ? val : `/${val}`);
+}
+
 export default function middleware(opts: {
 	manifest: Manifest,
 	store: (req: Req) => Store,
+	ignore?: any,
 	routes?: any // legacy
 }) {
 	if (opts.routes) {
@@ -84,12 +96,19 @@ export default function middleware(opts: {
 
 	const output = locations.dest();
 
-	const { manifest, store } = opts;
+	const { manifest, store, ignore } = opts;
 
 	let emitted_basepath = false;
 
 	const middleware = compose_handlers([
+		ignore && ((req: Req, res: ServerResponse, next: () => void) => {
+			req[IGNORE] = toIgnore(req.path, ignore);
+			next();
+		}),
+
 		(req: Req, res: ServerResponse, next: () => void) => {
+			if (req[IGNORE]) return next();
+
 			if (req.baseUrl === undefined) {
 				let { originalUrl } = req;
 				if (req.url === '/' && originalUrl[originalUrl.length - 1] !== '/') {
@@ -163,6 +182,8 @@ function serve({ prefix, pathname, cache_control }: {
 		: (file: string) => (cache.has(file) ? cache : cache.set(file, fs.readFileSync(path.resolve(output, file)))).get(file)
 
 	return (req: Req, res: ServerResponse, next: () => void) => {
+		if (req[IGNORE]) return next();
+
 		if (filter(req)) {
 			const type = lookup(req.path);
 
@@ -245,6 +266,8 @@ function get_server_route_handler(routes: ServerRoute[]) {
 	}
 
 	return function find_route(req: Req, res: ServerResponse, next: () => void) {
+		if (req[IGNORE]) return next();
+
 		for (const route of routes) {
 			if (route.pattern.test(req.path)) {
 				handle_route(route, req, res, next);
@@ -270,6 +293,8 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 	const { server_routes, pages } = manifest;
 	const error_route = manifest.error;
 
+	const should_wrap_data = dev() || process.env.SAPPER_EXPORT;
+
 	function handle_error(req: Req, res: ServerResponse, statusCode: number, error: Error | string) {
 		handle_page({
 			pattern: null,
@@ -292,6 +317,8 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 		let preloaded_chunks = Array.isArray(chunks.main) ? chunks.main : [chunks.main];
 		if (!error) {
 			page.parts.forEach(part => {
+				if (!part) return;
+
 				// using concat because it could be a string or an array. thanks webpack!
 				preloaded_chunks = preloaded_chunks.concat(chunks[part.name]);
 			});
@@ -366,6 +393,8 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 			: {};
 
 		Promise.all([root_preloaded].concat(page.parts.map(part => {
+			if (!part) return null;
+
 			return part.component.preload
 				? part.component.preload.call(preload_context, {
 					path: req.path,
@@ -378,10 +407,24 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 			return []; // appease TypeScript
 		}).then(preloaded => {
 			if (redirect) {
+				const location = `${req.baseUrl}/${redirect.location}`;
+
 				res.statusCode = redirect.statusCode;
-				res.setHeader('Location', `${req.baseUrl}/${redirect.location}`);
+				res.setHeader('Location', location);
 				res.end();
 
+				if (process.send) {
+					process.send({
+						__sapper__: true,
+						event: 'file',
+						url: req.url,
+						method: req.method,
+						status: redirect.statusCode,
+						type: 'text/html',
+						body: `<script>window.location.href = "${location}"</script>`
+					});
+				}
+
 				return;
 			}
 
@@ -390,11 +433,6 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 				return;
 			}
 
-			const serialized = {
-				preloaded: `[${preloaded.map(data => try_serialize(data)).join(',')}]`,
-				store: store && try_serialize(store.get())
-			};
-
 			const segments = req.path.split('/').filter(Boolean);
 
 			const props: Props = {
@@ -411,23 +449,37 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 
 			const data = Object.assign({}, props, preloaded[0], {
 				params: {},
-				child: {}
+				child: {
+					segment: segments[0]
+				}
 			});
 
+			// in dev and export modes, we wrap data in proxies to see
+			// how much of it is used in the initial render
+			const wrapped = should_wrap_data && wrap_data(preloaded);
+
+			// this is an easy way to 'reify' top-level values
+			const _preloaded = should_wrap_data
+				? wrapped.data.map((x: any) => x)
+				: preloaded;
+
 			let level = data.child;
 			for (let i = 0; i < page.parts.length; i += 1) {
 				const part = page.parts[i];
+				if (!part) continue;
+
 				const get_params = part.params || (() => ({}));
 
 				Object.assign(level, {
-					segment: segments[i],
 					component: part.component,
 					props: Object.assign({}, props, {
 						params: get_params(match)
-					}, preloaded[i + 1])
+					}, _preloaded[i + 1])
 				});
 
-				level.props.child = <Props["child"]>{};
+				level.props.child = <Props["child"]>{
+					segment: segments[i + 1]
+				};
 				level = level.props.child;
 			}
 
@@ -441,6 +493,47 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 				.map(file => `<script src='${req.baseUrl}/client/${file}'></script>`)
 				.join('');
 
+			const unwrapped = should_wrap_data && wrapped.unwrap();
+
+			const preloaded_serialized = preloaded.map(try_serialize);
+
+			if (should_wrap_data && process.send) {
+				const discrepancies = [];
+
+				unwrapped.forEach((clone, i) => {
+					const loaded = preloaded_serialized[i];
+					if (!loaded) return;
+
+					const rendered = try_serialize(clone);
+
+					if (rendered !== loaded) {
+						const part = page.parts[i - 1];
+						const file = part ? part.file : '_layout.html';
+
+						discrepancies.push({
+							file,
+							preloaded: loaded.length,
+							rendered: rendered.length,
+							props: list_unused_properties(preloaded[i], clone)
+						});
+					}
+				});
+
+				if (discrepancies.length) {
+					process.send({
+						__sapper__: true,
+						event: 'unused_data',
+						url: req.url,
+						discrepancies
+					});
+				}
+			}
+
+			const serialized = {
+				preloaded: `[${preloaded_serialized.join(',')}]`,
+				store: store && try_serialize(store.get())
+			};
+
 			let inline_script = `__SAPPER__={${[
 				error && `error:1`,
 				`baseUrl:"${req.baseUrl}"`,
@@ -464,12 +557,19 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 			res.end(body);
 
 			if (process.send) {
+				process.send({
+					__sapper__: true,
+					event: 'preload',
+					url: req.url,
+					size: serialized.preloaded.length
+				});
+
 				process.send({
 					__sapper__: true,
 					event: 'file',
 					url: req.url,
 					method: req.method,
-					status: 200,
+					status,
 					type: 'text/html',
 					body
 				});
@@ -485,7 +585,9 @@ function get_page_handler(manifest: Manifest, store_getter: (req: Req) => Store)
 		});
 	}
 
-	return function find_route(req: Req, res: ServerResponse) {
+	return function find_route(req: Req, res: ServerResponse, next: () => void) {
+		if (req[IGNORE]) return next();
+
 		if (!server_routes.some(route => route.pattern.test(req.path))) {
 			for (const page of pages) {
 				if (page.pattern.test(req.path)) {

src/middleware/list_unused_properties.ts

@@ -0,0 +1,34 @@
+export function list_unused_properties(all: any, used: any) {
+	const props: string[] = [];
+
+	const seen = new Set();
+
+	function walk(keypath: string, a: any, b: any) {
+		if (seen.has(a)) return;
+		seen.add(a);
+
+		if (!a || typeof a !== 'object') return;
+
+		const is_array = Array.isArray(a);
+
+		for (const key in a) {
+			const child_keypath = keypath
+				? is_array ? `${keypath}[${key}]` : `${keypath}.${key}`
+				: key;
+
+			if (hasProp.call(b, key)) {
+				const a_child = a[key];
+				const b_child = b[key];
+
+				walk(child_keypath, a_child, b_child);
+			} else {
+				props.push(child_keypath);
+			}
+		}
+	}
+
+	walk(null, all, used);
+	return props;
+}
+
+const hasProp = Object.prototype.hasOwnProperty;

src/middleware/wrap_data.ts

@@ -0,0 +1,85 @@
+type Obj = Record<string, any>;
+
+export function wrap_data(data: any) {
+	const proxies = new Map();
+	const clones = new Map();
+
+	const handler = {
+		get(target: any, property: string): any {
+			const value = target[property];
+			const intercepted = intercept(value);
+
+			const target_clone = clones.get(target);
+			const child_clone = clones.get(value);
+
+			if (target_clone && target.hasOwnProperty(property)) {
+				target_clone[property] = child_clone || value;
+			}
+
+			return intercepted;
+		},
+	};
+
+	function get_or_create_proxy(obj: any) {
+		if (!proxies.has(obj)) {
+			proxies.set(obj, new Proxy(obj, handler));
+		}
+
+		return proxies.get(obj);
+	}
+
+	function intercept(obj: any) {
+		if (clones.has(obj)) return obj;
+
+		if (obj && typeof obj === 'object') {
+			if (Array.isArray(obj)) {
+				clones.set(obj, []);
+				return get_or_create_proxy(obj);
+			}
+
+			else if (isPlainObject(obj)) {
+				clones.set(obj, {});
+				return get_or_create_proxy(obj);
+			}
+		}
+
+		clones.set(obj, obj);
+		return obj;
+	}
+
+	return {
+		data: intercept(data),
+		unwrap: () => {
+			return clones.get(data);
+		}
+	};
+}
+
+const objectProtoOwnPropertyNames = Object.getOwnPropertyNames(Object.prototype).sort().join('\0')
+
+function isPlainObject(obj: any) {
+	const proto = Object.getPrototypeOf(obj);
+
+	if (
+		proto !== Object.prototype &&
+		proto !== null &&
+		Object.getOwnPropertyNames(proto).sort().join('\0') !== objectProtoOwnPropertyNames
+	) {
+		return false;
+	}
+
+	if (Object.getOwnPropertySymbols(obj).length > 0) {
+		return false;
+	}
+
+	return true;
+}
+
+
+function pick(obj: Obj, props: string[]) {
+	const picked: Obj = {};
+	props.forEach(prop => {
+		picked[prop] = obj[prop];
+	});
+	return picked;
+}

src/runtime/index.ts

@@ -77,14 +77,14 @@ function select_route(url: URL): Target {
 
 let current_token: {};
 
-function render(data: any, changed_from: number, scroll: ScrollPosition, token: {}) {
+function render(data: any, nullable_depth: number, scroll: ScrollPosition, token: {}) {
 	if (current_token !== token) return;
 
 	if (root) {
 		// first, clear out highest-level root component
 		let level = data.child;
-		for (let i = 0; i < changed_from; i += 1) {
+		for (let i = 0; i < nullable_depth; i += 1) {
-			if (i === changed_from) break;
+			if (i === nullable_depth) break;
 			level = level.props.child;
 		}
 
@@ -134,7 +134,7 @@ let root_data: any;
 function prepare_page(target: Target): Promise<{
 	redirect?: Redirect;
 	data?: any;
-	changed_from?: number;
+	nullable_depth?: number;
 }> {
 	if (root) {
 		root.set({ preloading: true });
@@ -179,6 +179,7 @@ function prepare_page(target: Target): Promise<{
 
 	return Promise.all(page.parts.map(async (part, i) => {
 		if (i < changed_from) return null;
+		if (!part) return null;
 
 		const { default: Component } = await part.component();
 		const req = {
@@ -231,33 +232,42 @@ function prepare_page(target: Target): Promise<{
 		const data = {
 			path,
 			preloading: false,
-			child: Object.assign({}, root_props.child)
+			child: Object.assign({}, root_props.child, {
+				segment: segments[0]
+			})
 		};
 		if (changed(query, root_props.query)) data.query = query;
 		if (changed(params, root_props.params)) data.params = params;
 
 		let level = data.child;
+		let nullable_depth = 0;
+
 		for (let i = 0; i < page.parts.length; i += 1) {
 			const part = page.parts[i];
+			if (!part) continue;
+
 			const get_params = part.params || (() => ({}));
 
 			if (i < changed_from) {
 				level.props.path = path;
 				level.props.query = query;
 				level.props.child = Object.assign({}, level.props.child);
+
+				nullable_depth += 1;
 			} else {
-				level.segment = new_segments[i];
 				level.component = results[i].Component;
 				level.props = Object.assign({}, level.props, props, {
 					params: get_params(target.match),
 				}, results[i].preloaded);
+
 				level.props.child = {};
 			}
 
 			level = level.props.child;
+			level.segment = segments[i + 1];
 		}
 
-		return { data, changed_from };
+		return { data, nullable_depth };
 	});
 }
 
@@ -282,13 +292,13 @@ async function navigate(target: Target, id: number): Promise<any> {
 	prefetching = null;
 
 	const token = current_token = {};
-	const { redirect, data, changed_from } = await loaded;
+	const { redirect, data, nullable_depth } = await loaded;
 
 	if (redirect) {
 		await goto(redirect.location, { replaceState: true });
 	} else {
-		render(data, changed_from, scroll_history[id], token);
+		render(data, nullable_depth, scroll_history[id], token);
-		document.activeElement.blur();
+		if (document.activeElement) document.activeElement.blur();
 	}
 }
 
@@ -353,7 +363,7 @@ function handle_popstate(event: PopStateEvent) {
 
 let prefetching: {
 	href: string;
-	promise: Promise<{ redirect?: Redirect, data?: any, changed_from?: number }>;
+	promise: Promise<{ redirect?: Redirect, data?: any, nullable_depth?: number }>;
 } = null;
 
 export function prefetch(href: string) {

test/app/app/server.js

@@ -91,8 +91,14 @@ const middlewares = [
 			return new Store({
 				title: 'Stored title'
 			});
-		}
+		},
-	})
+		ignore: [
+			/foobar/i,
+			'/buzz',
+			'fizz',
+			x => x === '/hello'
+		]
+	}),
 ];
 
 if (BASEPATH) {
@@ -101,4 +107,8 @@ if (BASEPATH) {
 	app.use(...middlewares);
 }
 
+['foobar', 'buzz', 'fizzer', 'hello'].forEach(uri => {
+	app.get('/'+uri, (req, res) => res.end(uri));
+});
+
 app.listen(PORT);

test/app/routes/[x]/[y]/_layout.html

@@ -1,6 +1,8 @@
 <span>y: {segment} {count}</span>
 <svelte:component this={child.component} {...child.props}/>
 
+<span>child segment: {child.segment}</span>
+
 <script>
 	import counts from '../_counts.js';
 

test/app/routes/[x]/_layout.html

@@ -1,20 +0,0 @@
-<span>x: {segment} {count}</span>
-<svelte:component this={child.component} {...child.props}/>
-
-<script>
-	import counts from './_counts.js';
-
-	export default {
-		preload() {
-			return {
-				count: counts.x += 1
-			};
-		},
-
-		oncreate() {
-			this.set({
-				segment: this.get().params.x
-			});
-		}
-	};
-</script>

test/common/test.js

@@ -477,6 +477,42 @@ function run({ mode, basepath = '' }) {
 					});
 			});
 
+			// Ignores are meant for top-level escape.
+			// ~> Sapper **should** own the entire {basepath} when designated.
+			if (!basepath) {
+				it('respects `options.ignore` values (RegExp)', () => {
+					return nightmare.goto(`${base}/foobar`)
+						.evaluate(() => document.documentElement.textContent)
+						.then(text => {
+							assert.equal(text, 'foobar');
+						});
+				});
+
+				it('respects `options.ignore` values (String #1)', () => {
+					return nightmare.goto(`${base}/buzz`)
+						.evaluate(() => document.documentElement.textContent)
+						.then(text => {
+							assert.equal(text, 'buzz');
+						});
+				});
+
+				it('respects `options.ignore` values (String #2)', () => {
+					return nightmare.goto(`${base}/fizzer`)
+						.evaluate(() => document.documentElement.textContent)
+						.then(text => {
+							assert.equal(text, 'fizzer');
+						});
+				});
+
+				it('respects `options.ignore` values (Function)', () => {
+					return nightmare.goto(`${base}/hello`)
+						.evaluate(() => document.documentElement.textContent)
+						.then(text => {
+							assert.equal(text, 'hello');
+						});
+				});
+			}
+
 			it('does not attempt client-side navigation to server routes', () => {
 				return nightmare.goto(`${base}/blog/how-is-sapper-different-from-next`)
 					.init()
@@ -629,9 +665,9 @@ function run({ mode, basepath = '' }) {
 					.evaluate(() => document.querySelector('#sapper').textContent)
 					.then(text => {
 						assert.deepEqual(text.split('\n').filter(Boolean), [
-							'x: foo 1',
 							'y: bar 1',
-							'z: baz 1'
+							'z: baz 1',
+							'child segment: baz'
 						]);
 
 						return nightmare.click(`a`)
@@ -642,9 +678,9 @@ function run({ mode, basepath = '' }) {
 					})
 					.then(text => {
 						assert.deepEqual(text.split('\n').filter(Boolean), [
-							'x: foo 1',
 							'y: bar 1',
-							'z: qux 2'
+							'z: qux 2',
+							'child segment: qux'
 						]);
 					});
 			});

test/unit/create_routes/index.js

@@ -2,13 +2,6 @@ const path = require('path');
 const assert = require('assert');
 const { create_routes } = require('../../../dist/core.ts.js');
 
-
-const _default_layout = {
-	default: true,
-	name: '_default_layout',
-	file: null
-};
-
 describe('create_routes', () => {
 	it('creates routes', () => {
 		const { components, pages, server_routes } = create_routes(path.join(__dirname, 'samples/basic'));
@@ -21,7 +14,6 @@ describe('create_routes', () => {
 		assert.deepEqual(components, [
 			index,
 			about,
-			_default_layout,
 			blog,
 			blog_$slug
 		]);
@@ -44,7 +36,7 @@ describe('create_routes', () => {
 			{
 				pattern: /^\/blog\/?$/,
 				parts: [
-					{ component: _default_layout, params: [] },
+					null,
 					{ component: blog, params: [] }
 				]
 			},
@@ -52,7 +44,7 @@ describe('create_routes', () => {
 			{
 				pattern: /^\/blog\/([^\/]+?)\/?$/,
 				parts: [
-					{ component: _default_layout, params: [] },
+					null,
 					{ component: blog_$slug, params: ['slug'] }
 				]
 			}
@@ -110,15 +102,15 @@ describe('create_routes', () => {
 	it('sorts routes correctly', () => {
 		const { pages } = create_routes(path.join(__dirname, 'samples/sorting'));
 
-		assert.deepEqual(pages.map(p => p.parts.map(part => part.component.file)), [
+		assert.deepEqual(pages.map(p => p.parts.map(part => part && part.component.file)), [
 			['index.html'],
 			['about.html'],
-			[_default_layout.file, 'post/index.html'],
+			[null, 'post/index.html'],
-			[_default_layout.file, 'post/bar.html'],
+			[null, 'post/bar.html'],
-			[_default_layout.file, 'post/foo.html'],
+			[null, 'post/foo.html'],
-			[_default_layout.file, 'post/f[xx].html'],
+			[null, 'post/f[xx].html'],
-			[_default_layout.file, 'post/[id([0-9-a-z]{3,})].html'],
+			[null, 'post/[id([0-9-a-z]{3,})].html'],
-			[_default_layout.file, 'post/[id].html'],
+			[null, 'post/[id].html'],
 			['[wildcard].html']
 		]);
 	});