-> v0.3.2

handle nested routes

.gitignore

@@ -1,4 +1,5 @@
 .DS_Store
 node_modules
 cypress/screenshots
-test/app/.sapper
+test/app/.sapper
+runtime.js

CHANGELOG.md

@@ -1,5 +1,21 @@
 # sapper changelog
 
+## 0.3.2
+
+* Expose `prefetch` function ([#61](https://github.com/sveltejs/sapper/pull/61))
+
+## 0.3.1
+
+* Fix missing `runtime.js`
+
+## 0.3.0
+
+* Move `sapper/runtime/app.js` to `sapper/runtime.js`
+* Cancel navigation if overtaken by second navigation ([#48](https://github.com/sveltejs/sapper/issues/48))
+* Store preloaded data, to avoiding double prefetching ([#49](https://github.com/sveltejs/sapper/issues/49))
+* Pass server request object to `preload` ([#54](https://github.com/sveltejs/sapper/pull/54))
+* Nested routes ([#55](https://github.com/sveltejs/sapper/issues/55))
+
 ## 0.2.10
 
 * Handle deep links correctly ([#44](https://github.com/sveltejs/sapper/issues/44))

LICENSE

@@ -0,0 +1,9 @@
+Copyright (c) 2017 [these people](https://github.com/sveltejs/sapper/graphs/contributors).
+
+Permission is hereby granted by the authors of this software, to any person, to use the software for any purpose, free of charge, including the rights to run, read, copy, change, distribute and sell it, and including usage rights to any patents the authors may hold on it, subject to the following conditions:
+
+This license, or a link to its text, must be included with all copies of the software and any derivative works.
+
+Any modification to the software submitted to the authors may be incorporated into the software under the terms of this license.
+
+The software is provided "as is", without warranty of any kind, including but not limited to the warranties of title, fitness, merchantability and non-infringement. The authors have no obligation to provide support or updates for the software, and may not be held liable for any damages, claims or other liability arising from its use.

README.md

@@ -1,150 +1,37 @@
 # sapper
 
-Combat-ready apps, engineered by Svelte.
-
-## This is not a thing yet
-
-If you visit this README in a few weeks, hopefully it will have blossomed into the app development framework we deserve. Right now, it's just a set of ideas.
-
----
-
-[Next.js](https://github.com/zeit/next.js/) introduced a beautiful idea — that you should be able to build your app as universal React components in a special `pages` directory, and the framework should take care of routing and rendering on both client and server. What if we did the same thing for Svelte?
-
-High-level goals:
-
-* Extreme ease of development
-* Code-splitting and HMR out of the box (probably via webpack)
-* Best-in-class performance
-* As little magic as possible. Anyone should be able to understand how everything fits together, and e.g. make changes to the webpack config
-* Links are just `<a>` tags, no special `<Link>` components
+[Military-grade progressive web apps, powered by Svelte.](https://sapper.svelte.technology)
 
 
-## Design
+## What is Sapper?
 
-A Sapper app is just an Express app (conventionally, `server.js`) that uses the `sapper` middleware:
+Sapper is a framework for building high-performance universal web apps. [Read the guide](https://sapper.svelte.technology/guide) or the [introductory blog post](https://svelte.technology/blog/sapper-towards-the-ideal-web-app-framework) to learn more.
 
-```js
-const app = require('express')();
-const sapper = require('sapper');
 
-app.use(sapper());
+## Get started
 
-const { PORT = 3000 } = process.env;
-app.listen(PORT, () => {
-  console.log(`listening on port ${PORT}`);
-});
+Clone the [starter project template](https://github.com/sveltejs/sapper-template) with [degit](https://github.com/rich-harris/degit)...
+
+```bash
+npx degit sveltejs/sapper-template my-app
 ```
 
-The middleware serves pages that match files in the `routes` directory, and assets generated by webpack. In development mode, the middleware once activated watches `routes` to keep the app up-to-date.
+...then install dependencies and start the dev server...
 
-
-## Routing
-
-Like Next, routes are defined by the project directory structure, but with some crucial differences:
-
-* Files with an `.html` extension are treated as Svelte components. The `routes/about.html` (or `routes/about/index.html`) would create the `/about` route.
-* Files with a `.js` or `.mjs` extension are more generic route handlers. These files should export functions corresponding to the HTTP methods they support (example below).
-* Instead of route masking, we embed parameters in the filename. For example `post/[id].html` maps to `/post/:id`, and the component will be rendered with the appropriate parameter.
-* Nested routes (read [this article](https://joshduff.com/2015-06-why-you-need-a-state-router.md)) can be handled by creating a file that matches the subroute — for example, `routes/app/settings/[submenu].html` would match `/app/settings/profile` *and* `app/settings`, but in the latter case the `submenu` parameter would be `null`.
-
-An example of a generic route:
-
-```js
-// routes/api/post/[id].js
-export async function get(req, res) {
-  try {
-    const data = await getPostFromDatabase(req.params.id);
-    const json = JSON.stringify(data);
-
-    res.set({
-      'Content-Type': 'application/json',
-      'Content-Length': json.length
-    });
-
-    res.send(json);
-  } catch (err) {
-    res.status(500).send(err.message);
-  }
-}
+```bash
+cd my-app
+npm install
+npm run dev
 ```
 
-Or, if you omit the `res` argument, it can use the return value:
+...and navigate to [localhost:3000](http://localhost:3000). To build and run in production mode:
 
-```js
-// routes/api/post/[id].js
-export async function get(req) {
-  return await getPostFromDatabase(req.params.id);
-}
+```bash
+npm run build
+npm start
 ```
 
 
-## Client-side app
+## License
 
-Sapper will create (and in development mode, update) a barebones `main.js` file that dynamically imports individual routes and renders them — something like this:
-
-```js
-window.addEventListener('click', event => {
-  let a = event.target;
-  while (a && a.nodeName !== 'A') a = a.parentNode;
-  if (!a) return;
-
-  if (navigate(new URL(a.href))) event.preventDefault();
-});
-
-const target = document.querySelector('#sapper');
-let component;
-
-function navigate(url) {
-  if (url.origin !== window.location.origin) return;
-
-  let match;
-  let params = {};
-  const query = {};
-
-  function render(mod) {
-    if (component) {
-      component.destroy();
-    } else {
-      target.innerHTML = '';
-    }
-
-    component = new mod.default({
-      target,
-      data: { query, params },
-      hydrate: !!component
-    });
-  }
-
-  if (url.pathname === '/about') {
-    import('/about/index.html').then(render);
-  } else if (url.pathname === '/') {
-    import('/index.js').then(render);
-  } else if (match = /^\/post\/([^\/]+)$/.exec(url.pathname)) {
-    params.id = match[1];
-    import('/post/[id].html').then(render);
-  } else if (match = /^\/([^\/]+)$/.exec(url.pathname)) {
-    params.wildcard = match[1];
-    import('/[wildcard].html').then(render);
-  }
-
-  return true;
-}
-
-navigate(window.location);
-```
-
-We're glossing over a lot of important stuff here — e.g. handling `popstate` — but you get the idea. Knowledge of all the possible routes means we can generate optimal code, much in the same way that statically analysing Svelte templates allows the compiler to generate optimal code.
-
-
-## Things to figure out
-
-* How to customise the overall page template
-* An equivalent of `getInitialProps`
-* Critical CSS
-* `store` integration
-* Route transitions
-* Equivalent of `next export`
-* A good story for realtime/GraphQL stuff
-* Service worker
-* Using `Link...rel=preload` headers to push main.js/[route].js plus styles
-* ...and lots of other things that haven't occurred to me yet.
+[LIL](LICENSE)

lib/index.js

@@ -151,7 +151,7 @@ function get_route_handler(fn) {
 						const data = { params: req.params, query: req.query };
 
 						if (mod.preload) {
-							const promise = Promise.resolve(mod.preload(data)).then(preloaded => {
+							const promise = Promise.resolve(mod.preload(req)).then(preloaded => {
 								Object.assign(data, preloaded);
 								return mod.render(data);
 							});

lib/utils/create_routes.js

@@ -16,9 +16,22 @@ module.exports = function create_matchers(files) {
 				.filter(part => part[0] === '[')
 				.map(part => part.slice(1, -1));
 
-			const pattern = new RegExp(
-				`^\\/${parts.map(p => p[0] === '[' ? '([^/]+)' : p).join('\\/')}$`
-			);
+			let pattern_string = '';
+			let i = parts.length;
+			let nested = true;
+			while (i--) {
+				const part = parts[i];
+				const dynamic = part[0] === '[';
+
+				if (dynamic) {
+					pattern_string = nested ? `(?:\\/([^/]+)${pattern_string})?` : `\\/([^/]+)${pattern_string}`;
+				} else {
+					nested = false;
+					pattern_string = `\\/${part}${pattern_string}`;
+				}
+			}
+
+			const pattern = new RegExp(`^${pattern_string || '\\/'}$`);
 
 			const test = url => pattern.test(url);
 
@@ -58,8 +71,8 @@ module.exports = function create_matchers(files) {
 					return 0;
 				}
 
-				if (!a_part) return 1;
-				if (!b_part) return -1;
+				if (!a_part) return -1;
+				if (!b_part) return 1;
 
 				const a_is_dynamic = a_part[0] === '[';
 				const b_is_dynamic = b_part[0] === '[';

lib/utils/generate_asset_cache.js

@@ -59,10 +59,10 @@ function generate_service_worker(chunk_files) {
 	}]`;
 
 	return read('templates/service-worker.js')
-		.replace('__timestamp__', Date.now())
-		.replace('__assets__', JSON.stringify(assets))
-		.replace('__shell__', JSON.stringify(chunk_files.concat('/index.html')))
-		.replace('__routes__', route_code);
+		.replace(/__timestamp__/g, Date.now())
+		.replace(/__assets__/g, JSON.stringify(assets))
+		.replace(/__shell__/g, JSON.stringify(chunk_files.concat('/index.html')))
+		.replace(/__routes__/g, route_code);
 }
 
 function generate_index(main_file) {

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "sapper",
-  "version": "0.2.7",
+  "version": "0.2.10",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -790,6 +790,12 @@
       "integrity": "sha512-b0553uYA5YAEGgyYIGYROzKQ7X5RAqedkfjiZxwi0kL1g3bOaBNNZfYkzt/CL0umgD5wc9Jec2FbB98CjkMRvQ==",
       "dev": true
     },
+    "compare-versions": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/compare-versions/-/compare-versions-2.0.1.tgz",
+      "integrity": "sha1-Htwfk2h/2XoyXFn1XkWgfbEGrKY=",
+      "dev": true
+    },
     "concat-map": {
       "version": "0.0.1",
       "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
@@ -1707,6 +1713,12 @@
       "resolved": "https://registry.npmjs.org/estraverse/-/estraverse-4.2.0.tgz",
       "integrity": "sha1-De4/7TH81GlhjOc0IJn8GvoL2xM="
     },
+    "estree-walker": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-0.2.1.tgz",
+      "integrity": "sha1-va/oCVOD2EFNXcLs9MkXO225QS4=",
+      "dev": true
+    },
     "esutils": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/esutils/-/esutils-2.0.2.tgz",
@@ -5583,6 +5595,43 @@
         "inherits": "2.0.3"
       }
     },
+    "rollup": {
+      "version": "0.53.0",
+      "resolved": "https://registry.npmjs.org/rollup/-/rollup-0.53.0.tgz",
+      "integrity": "sha512-bG5RzkF7wcOHmKoVAFtERZ5P9TNJP9/AF+ldwGm/Rx6pejura+Z9BDU0GJtzWu+lYXwjfINmgiCclhLJzP/OXA==",
+      "dev": true
+    },
+    "rollup-plugin-typescript": {
+      "version": "0.8.1",
+      "resolved": "https://registry.npmjs.org/rollup-plugin-typescript/-/rollup-plugin-typescript-0.8.1.tgz",
+      "integrity": "sha1-L/fuzCHPa7K0P8J+W2iJUs5xkko=",
+      "dev": true,
+      "requires": {
+        "compare-versions": "2.0.1",
+        "object-assign": "4.1.1",
+        "rollup-pluginutils": "1.5.2",
+        "tippex": "2.3.1",
+        "typescript": "1.8.10"
+      },
+      "dependencies": {
+        "typescript": {
+          "version": "1.8.10",
+          "resolved": "https://registry.npmjs.org/typescript/-/typescript-1.8.10.tgz",
+          "integrity": "sha1-tHXW4N/wv1DyluXKbvn7tccyDx4=",
+          "dev": true
+        }
+      }
+    },
+    "rollup-pluginutils": {
+      "version": "1.5.2",
+      "resolved": "https://registry.npmjs.org/rollup-pluginutils/-/rollup-pluginutils-1.5.2.tgz",
+      "integrity": "sha1-HhVud4+UtyVb+hs9AXi+j1xVJAg=",
+      "dev": true,
+      "requires": {
+        "estree-walker": "0.2.1",
+        "minimatch": "3.0.4"
+      }
+    },
     "run-async": {
       "version": "2.3.0",
       "resolved": "https://registry.npmjs.org/run-async/-/run-async-2.3.0.tgz",
@@ -6191,6 +6240,12 @@
         "setimmediate": "1.0.5"
       }
     },
+    "tippex": {
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/tippex/-/tippex-2.3.1.tgz",
+      "integrity": "sha1-ov1bcIfXy/sgyYBqbBYQjCwPr9o=",
+      "dev": true
+    },
     "tmp": {
       "version": "0.0.33",
       "resolved": "https://registry.npmjs.org/tmp/-/tmp-0.0.33.tgz",
@@ -6229,6 +6284,12 @@
       "integrity": "sha1-WIeWa7WCpFA6QetST301ARgVphM=",
       "dev": true
     },
+    "tslib": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/tslib/-/tslib-1.8.1.tgz",
+      "integrity": "sha1-aUavLR1lGnsYY7Ux1uWvpBqkTqw=",
+      "dev": true
+    },
     "tty-browserify": {
       "version": "0.0.0",
       "resolved": "https://registry.npmjs.org/tty-browserify/-/tty-browserify-0.0.0.tgz",
@@ -6275,6 +6336,12 @@
       "integrity": "sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c=",
       "dev": true
     },
+    "typescript": {
+      "version": "2.6.2",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-2.6.2.tgz",
+      "integrity": "sha1-PFtv1/beCRQmkCfwPAlGdY92c6Q=",
+      "dev": true
+    },
     "uglify-js": {
       "version": "2.8.29",
       "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-2.8.29.tgz",

package.json

@@ -1,11 +1,18 @@
 {
   "name": "sapper",
-  "version": "0.2.10",
+  "version": "0.3.2",
   "description": "Military-grade apps, engineered by Svelte",
   "main": "lib/index.js",
   "bin": {
     "sapper": "cli/index.js"
   },
+  "files": [
+    "cli",
+    "lib",
+    "runtime",
+    "runtime.js",
+    "webpack"
+  ],
   "directories": {
     "test": "test"
   },
@@ -30,14 +37,21 @@
     "nightmare": "^2.10.0",
     "node-fetch": "^1.7.3",
     "npm-run-all": "^4.1.2",
+    "rollup": "^0.53.0",
+    "rollup-plugin-typescript": "^0.8.1",
     "style-loader": "^0.19.1",
     "svelte": "^1.49.1",
     "svelte-loader": "^2.3.2",
+    "tslib": "^1.8.1",
+    "typescript": "^2.6.2",
     "wait-on": "^2.0.2"
   },
   "scripts": {
     "cy:open": "cypress open",
-    "test": "mocha --opts mocha.opts"
+    "test": "mocha --opts mocha.opts",
+    "pretest": "npm run build",
+    "build": "rollup -c",
+    "dev": "rollup -cw"
   },
   "repository": "https://github.com/sveltejs/sapper",
   "keywords": [

rollup.config.js

@@ -0,0 +1,17 @@
+import typescript from 'rollup-plugin-typescript';
+
+export default [
+	// runtime.js
+	{
+		input: 'src/runtime/index.ts',
+		output: {
+			file: 'runtime.js',
+			format: 'es'
+		},
+		plugins: [
+			typescript({
+				typescript: require('typescript')
+			})
+		]
+	}
+];

runtime/app.js

@@ -1,211 +1,2 @@
-const detach = node => {
-	node.parentNode.removeChild(node);
-};
-
-export let component;
-let target;
-let routes;
-
-const history = typeof window !== 'undefined' ? window.history : {
-	pushState: () => {},
-	replaceState: () => {},
-};
-
-const scroll_history = {};
-let uid = 1;
-let cid;
-
-if ('scrollRestoration' in history) {
-	history.scrollRestoration = 'manual';
-}
-
-function select_route(url) {
-	if (url.origin !== window.location.origin) return null;
-
-	for (const route of routes) {
-		const match = route.pattern.exec(url.pathname);
-		if (match) {
-			const params = route.params(match);
-
-			const query = {};
-			for (const [key, value] of url.searchParams) query[key] = value || true;
-
-			return { route, data: { params, query } };
-		}
-	}
-}
-
-function render(Component, data, scroll) {
-	Promise.resolve(
-		Component.preload ? Component.preload(data) : {}
-	).then(preloaded => {
-		if (component) {
-			component.destroy();
-		} else {
-			// first load — remove SSR'd <head> contents
-			const start = document.querySelector('#sapper-head-start');
-			const end = document.querySelector('#sapper-head-end');
-
-			if (start && end) {
-				while (start.nextSibling !== end) detach(start.nextSibling);
-				detach(start);
-				detach(end);
-			}
-
-			// preload additional routes
-			routes.reduce((promise, route) => promise.then(route.load), Promise.resolve());
-		}
-
-		component = new Component({
-			target,
-			data: Object.assign(data, preloaded),
-			hydrate: !!component
-		});
-
-		if (scroll) {
-			window.scrollTo(scroll.x, scroll.y);
-		}
-	});
-}
-
-function navigate(url, id) {
-	const selected = select_route(url);
-	if (selected) {
-		if (id) {
-			// popstate or initial navigation
-			cid = id;
-		} else {
-			// clicked on a link. preserve scroll state
-			scroll_history[cid] = scroll_state();
-
-			id = cid = ++uid;
-			scroll_history[cid] = { x: 0, y: 0 };
-		}
-
-		selected.route.load().then(mod => {
-			render(mod.default, selected.data, scroll_history[id]);
-		});
-
-		cid = id;
-		return true;
-	}
-}
-
-function handle_click(event) {
-	// Adapted from https://github.com/visionmedia/page.js
-	// MIT license https://github.com/visionmedia/page.js#license
-	if (which(event) !== 1) return;
-	if (event.metaKey || event.ctrlKey || event.shiftKey) return;
-	if (event.defaultPrevented) return;
-
-	const a = findAnchor(event.target);
-	if (!a) return;
-
-	// check if link is inside an svg
-	// in this case, both href and target are always inside an object
-	const svg = typeof a.href === 'object' && a.href.constructor.name === 'SVGAnimatedString';
-	const href = svg ? a.href.baseVal : a.href;
-
-	if (href === window.location.href) {
-		event.preventDefault();
-		return;
-	}
-
-	// Ignore if tag has
-	// 1. 'download' attribute
-	// 2. rel='external' attribute
-	if (a.hasAttribute('download') || a.getAttribute('rel') === 'external') return;
-
-	// Ignore if <a> has a target
-	if (svg ? a.target.baseVal : a.target) return;
-
-	const url = new URL(href);
-
-	// Don't handle hash changes
-	if (url.pathname === window.location.pathname && url.search === window.location.search) return;
-
-	if (navigate(url, null)) {
-		event.preventDefault();
-		history.pushState({ id: cid }, '', url.href);
-	}
-}
-
-function handle_popstate(event) {
-	scroll_history[cid] = scroll_state();
-
-	if (event.state) {
-		navigate(new URL(window.location), event.state.id);
-	} else {
-		// hashchange
-		cid = ++uid;
-		history.replaceState({ id: cid }, '', window.location.href);
-	}
-}
-
-function prefetch(event) {
-	const a = findAnchor(event.target);
-	if (!a || a.rel !== 'prefetch') return;
-
-	const selected = select_route(new URL(a.href));
-
-	if (selected) {
-		selected.route.load().then(mod => {
-			if (mod.default.preload) mod.default.preload(selected.data);
-		});
-	}
-}
-
-function findAnchor(node) {
-	while (node && node.nodeName.toUpperCase() !== 'A') node = node.parentNode; // SVG <a> elements have a lowercase name
-	return node;
-}
-
-let inited;
-
-export function init(_target, _routes) {
-	target = _target;
-	routes = _routes;
-
-	if (!inited) { // this check makes HMR possible
-		window.addEventListener('click', handle_click);
-		window.addEventListener('popstate', handle_popstate);
-
-		// prefetch
-		window.addEventListener('touchstart', prefetch);
-		window.addEventListener('mouseover', prefetch);
-
-		inited = true;
-	}
-
-	setTimeout(() => {
-		const { hash, href } = window.location;
-
-		const deep_linked = hash && document.querySelector(hash);
-		scroll_history[uid] = deep_linked ?
-			{ x: 0, y: deep_linked.getBoundingClientRect().top } :
-			scroll_state();
-
-		history.replaceState({ id: uid }, '', href);
-		navigate(new URL(window.location), uid);
-	});
-}
-
-function which(event) {
-	event = event || window.event;
-	return event.which === null ? event.button : event.which;
-}
-
-function scroll_state() {
-	return {
-		x: window.scrollX,
-		y: window.scrollY
-	};
-}
-
-export function goto(href, opts = {}) {
-	if (navigate(new URL(href, window.location.href))) {
-		if (history) history[opts.replaceState ? 'replaceState' : 'pushState']({ id: cid }, '', href);
-	} else {
-		window.location.href = href;
-	}
-}
+console.error('sapper/runtime/app.js has been deprecated in favour of sapper/runtime.js');
+export * from '../runtime.js';

src/runtime/index.ts

@@ -0,0 +1,221 @@
+import { detach, findAnchor, scroll_state, which } from './utils';
+import { Component, ComponentConstructor, Params, Query, Route, RouteData, ScrollPosition } from './interfaces';
+
+export let component: Component;
+let target: Node;
+let routes: Route[];
+
+const history = typeof window !== 'undefined' ? window.history : {
+	pushState: (state: any, title: string, href: string) => {},
+	replaceState: (state: any, title: string, href: string) => {},
+	scrollRestoration: ''
+};
+
+const scroll_history: Record<string, ScrollPosition> = {};
+let uid = 1;
+let cid: number;
+
+if ('scrollRestoration' in history) {
+	history.scrollRestoration = 'manual';
+}
+
+function select_route(url: URL): { route: Route, data: RouteData } {
+	if (url.origin !== window.location.origin) return null;
+
+	for (const route of routes) {
+		const match = route.pattern.exec(url.pathname);
+		if (match) {
+			const params = route.params(match);
+
+			const query: Record<string, string | true> = {};
+			for (const [key, value] of url.searchParams) query[key] = value || true;
+
+			return { route, data: { params, query } };
+		}
+	}
+}
+
+let current_token: {};
+
+function render(Component: ComponentConstructor, data: any, scroll: ScrollPosition, token: {}) {
+	if (current_token !== token) return;
+
+	if (component) {
+		component.destroy();
+	} else {
+		// first load — remove SSR'd <head> contents
+		const start = document.querySelector('#sapper-head-start');
+		const end = document.querySelector('#sapper-head-end');
+
+		if (start && end) {
+			while (start.nextSibling !== end) detach(start.nextSibling);
+			detach(start);
+			detach(end);
+		}
+
+		// preload additional routes
+		routes.reduce((promise: Promise<any>, route) => promise.then(route.load), Promise.resolve());
+	}
+
+	component = new Component({
+		target,
+		data,
+		hydrate: !!component
+	});
+
+	if (scroll) {
+		window.scrollTo(scroll.x, scroll.y);
+	}
+}
+
+function prepare_route(Component, data) {
+	return Promise.resolve(
+		Component.preload ? Component.preload(data) : {}
+	).then(preloaded => {
+		Object.assign(data, preloaded)
+		return { Component, data };
+	});
+}
+
+function navigate(url: URL, id: number) {
+	const selected = select_route(url);
+	if (selected) {
+		if (id) {
+			// popstate or initial navigation
+			cid = id;
+		} else {
+			// clicked on a link. preserve scroll state
+			scroll_history[cid] = scroll_state();
+
+			id = cid = ++uid;
+			scroll_history[cid] = { x: 0, y: 0 };
+		}
+
+		const loaded = prefetching && prefetching.href === url.href ?
+			prefetching.promise :
+			selected.route.load().then(mod => prepare_route(mod.default, selected.data));
+
+		prefetching = null;
+
+		const token = current_token = {};
+
+		loaded.then(({ Component, data }) => {
+			render(Component, data, scroll_history[id], token);
+		});
+
+		cid = id;
+		return true;
+	}
+}
+
+function handle_click(event: MouseEvent) {
+	// Adapted from https://github.com/visionmedia/page.js
+	// MIT license https://github.com/visionmedia/page.js#license
+	if (which(event) !== 1) return;
+	if (event.metaKey || event.ctrlKey || event.shiftKey) return;
+	if (event.defaultPrevented) return;
+
+	const a: HTMLAnchorElement | SVGAElement = <HTMLAnchorElement | SVGAElement>findAnchor(<Node>event.target);
+	if (!a) return;
+
+	// check if link is inside an svg
+	// in this case, both href and target are always inside an object
+	const svg = typeof a.href === 'object' && a.href.constructor.name === 'SVGAnimatedString';
+	const href = String(svg ? (<SVGAElement>a).href.baseVal : a.href);
+
+	if (href === window.location.href) {
+		event.preventDefault();
+		return;
+	}
+
+	// Ignore if tag has
+	// 1. 'download' attribute
+	// 2. rel='external' attribute
+	if (a.hasAttribute('download') || a.getAttribute('rel') === 'external') return;
+
+	// Ignore if <a> has a target
+	if (svg ? (<SVGAElement>a).target.baseVal : a.target) return;
+
+	const url = new URL(href);
+
+	// Don't handle hash changes
+	if (url.pathname === window.location.pathname && url.search === window.location.search) return;
+
+	if (navigate(url, null)) {
+		event.preventDefault();
+		history.pushState({ id: cid }, '', url.href);
+	}
+}
+
+function handle_popstate(event: PopStateEvent) {
+	scroll_history[cid] = scroll_state();
+
+	if (event.state) {
+		navigate(new URL(window.location.href), event.state.id);
+	} else {
+		// hashchange
+		cid = ++uid;
+		history.replaceState({ id: cid }, '', window.location.href);
+	}
+}
+
+let prefetching: {
+	href: string;
+	promise: Promise<{ Component: ComponentConstructor, data: any }>;
+} = null;
+
+export function prefetch(href: string) {
+	const selected = select_route(new URL(href));
+
+	if (selected) {
+		prefetching = {
+			href,
+			promise: selected.route.load().then(mod => prepare_route(mod.default, selected.data))
+		};
+	}
+}
+
+function handle_touchstart_mouseover(event: MouseEvent | TouchEvent) {
+        const a: HTMLAnchorElement = <HTMLAnchorElement>findAnchor(<Node>event.target);
+        if (!a || a.rel !== 'prefetch') return;
+
+        prefetch(a.href);
+}
+
+let inited: boolean;
+
+export function init(_target: Node, _routes: Route[]) {
+	target = _target;
+	routes = _routes;
+
+	if (!inited) { // this check makes HMR possible
+		window.addEventListener('click', handle_click);
+		window.addEventListener('popstate', handle_popstate);
+
+		// prefetch
+		window.addEventListener('touchstart', handle_touchstart_mouseover);
+		window.addEventListener('mouseover', handle_touchstart_mouseover);
+
+		inited = true;
+	}
+
+	setTimeout(() => {
+		const { hash, href } = window.location;
+
+		const deep_linked = hash && document.querySelector(hash);
+		scroll_history[uid] = deep_linked ?
+			{ x: 0, y: deep_linked.getBoundingClientRect().top } :
+			scroll_state();
+
+		history.replaceState({ id: uid }, '', href);
+		navigate(new URL(window.location.href), uid);
+	});
+}
+
+export function goto(href: string, opts = { replaceState: false }) {
+	if (navigate(new URL(href, window.location.href), null)) {
+		if (history) history[opts.replaceState ? 'replaceState' : 'pushState']({ id: cid }, '', href);
+	} else {
+		window.location.href = href;
+	}
+}

src/runtime/interfaces.ts

@@ -0,0 +1,23 @@
+export type Params = Record<string, string>;
+export type Query = Record<string, string | true>;
+export type RouteData = { params: Params, query: Query };
+
+export interface ComponentConstructor {
+	new (options: { target: Node, data: any, hydrate: boolean }): Component;
+	preload: (data: { params: Params, query: Query }) => Promise<any>;
+};
+
+export interface Component {
+	destroy: () => void;
+}
+
+export type Route = {
+	pattern: RegExp;
+	params: (match: RegExpExecArray) => Record<string, string>;
+	load: () => Promise<{ default: ComponentConstructor }>
+};
+
+export type ScrollPosition = {
+	x: number;
+	y: number;
+};

src/runtime/utils.ts

@@ -0,0 +1,19 @@
+export function detach(node: Node) {
+	node.parentNode.removeChild(node);
+}
+
+export function findAnchor(node: Node) {
+	while (node && node.nodeName.toUpperCase() !== 'A') node = node.parentNode; // SVG <a> elements have a lowercase name
+	return node;
+}
+
+export function which(event: MouseEvent) {
+	return event.which === null ? event.button : event.which;
+}
+
+export function scroll_state() {
+	return {
+		x: window.scrollX,
+		y: window.scrollY
+	};
+}

test/app/routes/_components/Nav.html

@@ -1,10 +1,8 @@
 <nav>
 	<ul>
-		<li><a class='{{page === "home"  ? "selected" : ""}}' href='/'>home</a></li>
-		<li><a class='{{page === "about"  ? "selected" : ""}}' href='/about'>about</a></li>
-
-		<!-- for the blog link, we're using rel=prefetch so that Sapper prefetches
-		     the blog data when we hover over the link or tap it on a touchscreen -->
+		<li><a href='/'>home</a></li>
+		<li><a href='/about'>about</a></li>
+		<li><a href='/slow-preload'>slow preload</a></li>
 		<li><a rel=prefetch class='{{page === "blog"  ? "selected" : ""}}' href='/blog'>blog</a></li>
 	</ul>
 </nav>

test/app/routes/about.html

@@ -7,12 +7,13 @@
 
 	<p>This is the 'about' page. There's not much here.</p>
 
-	<button on:click='goto("/blog/what-is-sapper")'>What is Sapper?</button>
+	<button class='goto' on:click='goto("/blog/what-is-sapper")'>What is Sapper?</button>
+	<button class='prefetch' on:click='goto("/blog/why-the-name")'>Why the name?</button>
 </Layout>
 
 <script>
 	import Layout from './_components/Layout.html';
-	import { goto } from '../../../runtime/app.js';
+	import { goto, prefetch } from '../../../runtime.js';
 
 	export default {
 		components: {
@@ -20,7 +21,8 @@
 		},
 
 		methods: {
-			goto
+			goto,
+			prefetch
 		}
 	};
 </script>

test/app/routes/api/blog/[slug].js

@@ -13,7 +13,7 @@ export function get(req, res, next) {
 	if (slug in lookup) {
 		res.set({
 			'Content-Type': 'application/json',
-			'Cache-Control': `max-age=${30 * 60 * 1e3}` // cache for 30 minutes
+			'Cache-Control': `no-cache`
 		});
 
 		res.end(lookup[slug]);

test/app/routes/show-url.html

@@ -0,0 +1,9 @@
+<p>URL is {{url}}</p>
+
+<script>
+	export default {
+		preload({ url }) {
+			return { url };
+		}
+	};
+</script>

test/app/routes/slow-preload.html

@@ -0,0 +1,11 @@
+<h1>This page should never render</h1>
+
+<script>
+	export default {
+		preload() {
+			return new Promise(fulfil => {
+				window.fulfil = fulfil;
+			});
+		}
+	};
+</script>

test/app/templates/main.js

@@ -1,4 +1,4 @@
-import { init } from '../../../runtime/app.js';
+import { init } from '../../../runtime.js';
 
 // `routes` is an array of route objects injected by Sapper
 init(document.querySelector('#sapper'), __routes__);

test/common/test.js

@@ -11,7 +11,7 @@ run('development');
 
 function run(env) {
 	describe(`env=${env}`, function () {
-		this.timeout(5000);
+		this.timeout(20000);
 
 		let PORT;
 		let server;
@@ -166,7 +166,7 @@ function run(env) {
 			});
 
 			it('navigates to a new page without reloading', async () => {
-				await nightmare.goto(base).wait(() => window.READY).wait(100);
+				await nightmare.goto(base).wait(() => window.READY).wait(200);
 
 				const requests = await capture(async () => {
 					await nightmare.click('a[href="/about"]');
@@ -189,7 +189,7 @@ function run(env) {
 				await nightmare
 					.goto(`${base}/about`)
 					.wait(() => window.READY)
-					.click('button')
+					.click('.goto')
 					.wait(() => window.location.pathname === '/blog/what-is-sapper')
 					.wait(100);
 
@@ -199,6 +199,20 @@ function run(env) {
 				);
 			});
 
+			it('prefetches programmatically', async () => {
+				await nightmare
+					.goto(`${base}/about`)
+					.wait(() => window.READY);
+
+				const requests = await capture(async () => {
+					return await nightmare
+						.click('.prefetch')
+						.wait(100);
+				});
+
+				assert.ok(!!requests.find(r => r.url === '/api/blog/why-the-name'));
+			});
+
 			it('scrolls to active deeplink', async () => {
 				const scrollY = await nightmare
 					.goto(`${base}/blog/a-very-long-post#four`)
@@ -208,6 +222,73 @@ function run(env) {
 
 				assert.ok(scrollY > 0, scrollY);
 			});
+
+			it('reuses prefetch promise', async () => {
+				await nightmare
+					.goto(`${base}/blog`)
+					.wait(() => window.READY)
+					.wait(200);
+
+				const mouseover_requests = (await capture(async () => {
+					await nightmare
+						.mouseover('[href="/blog/what-is-sapper"]')
+						.wait(200);
+				})).map(r => r.url);
+
+				assert.deepEqual(mouseover_requests, [
+					'/api/blog/what-is-sapper'
+				]);
+
+				const click_requests = (await capture(async () => {
+					await nightmare
+						.click('[href="/blog/what-is-sapper"]')
+						.wait(200);
+				})).map(r => r.url);
+
+				assert.deepEqual(click_requests, []);
+			});
+
+			it('cancels navigation if subsequent navigation occurs during preload', async () => {
+				await nightmare
+					.goto(base)
+					.wait(() => window.READY)
+					.click('a[href="/slow-preload"]')
+					.wait(100)
+					.click('a[href="/about"]')
+					.wait(100);
+
+				assert.equal(
+					await nightmare.path(),
+					'/about'
+				);
+
+				assert.equal(
+					await nightmare.evaluate(() => document.querySelector('h1').textContent),
+					'About this site'
+				);
+
+				await nightmare
+					.evaluate(() => window.fulfil({}))
+					.wait(100);
+
+				assert.equal(
+					await nightmare.path(),
+					'/about'
+				);
+
+				assert.equal(
+					await nightmare.evaluate(() => document.querySelector('h1').textContent),
+					'About this site'
+				);
+			});
+
+			it('passes entire request object to preload', async () => {
+				const html = await nightmare
+					.goto(`${base}/show-url`)
+					.evaluate(() => document.querySelector('p').innerHTML);
+
+				assert.equal(html, `URL is /show-url`);
+			});
 		});
 
 		describe('headers', () => {

test/unit/create_routes.test.js

@@ -10,12 +10,12 @@ describe('create_routes', () => {
 		assert.deepEqual(
 			routes.map(r => r.file),
 			[
+				'index.html',
+				'about.html',
 				'post/foo.html',
 				'post/bar.html',
 				'post/[id].html',
-				'about.html',
-				'[wildcard].html',
-				'index.html'
+				'[wildcard].html'
 			]
 		);
 	});
@@ -45,8 +45,8 @@ describe('create_routes', () => {
 		assert.deepEqual(
 			routes.map(r => r.file),
 			[
-				'e/f/g/h.html',
-				'index.html'
+				'index.html',
+				'e/f/g/h.html'
 			]
 		);
 	});
@@ -71,4 +71,44 @@ describe('create_routes', () => {
 			create_routes(['[foo].html', '[bar]/index.html']);
 		}, /The \[foo\].html and \[bar\]\/index.html routes clash/);
 	});
+
+	it('matches nested routes', () => {
+		const route = create_routes(['settings/[submenu].html'])[0];
+
+		assert.deepEqual(route.exec('/settings/foo'), {
+			submenu: 'foo'
+		});
+
+		assert.deepEqual(route.exec('/settings'), {
+			submenu: null
+		});
+	});
+
+	it('prefers index routes to nested routes', () => {
+		const routes = create_routes(['settings/[submenu].html', 'settings.html']);
+
+		assert.deepEqual(
+			routes.map(r => r.file),
+			['settings.html', 'settings/[submenu].html']
+		);
+	});
+
+	it('matches deeply nested routes', () => {
+		const route = create_routes(['settings/[a]/[b]/index.html'])[0];
+
+		assert.deepEqual(route.exec('/settings/foo/bar'), {
+			a: 'foo',
+			b: 'bar'
+		});
+
+		assert.deepEqual(route.exec('/settings/foo'), {
+			a: 'foo',
+			b: null
+		});
+
+		assert.deepEqual(route.exec('/settings'), {
+			a: null,
+			b: null
+		});
+	});
 });

tsconfig.json

@@ -0,0 +1,18 @@
+{
+    "compilerOptions": {
+        "diagnostics": true,
+        "noImplicitThis": true,
+        "noImplicitAny": true,
+        "noEmitOnError": true,
+        "allowJs": true,
+        "lib": ["es5", "es6", "dom"],
+        "importHelpers": true
+    },
+    "target": "ES5",
+    "include": [
+        "src"
+    ],
+    "exclude": [
+        "node_modules"
+    ]
+}

webpack/config.js

@@ -1,5 +1,4 @@
-const path = require('path');
-const { src, dest, dev, entry } = require('../lib/config.js');
+const { dest, dev, entry } = require('../lib/config.js');
 
 module.exports = {
 	dev,
@@ -25,7 +24,7 @@ module.exports = {
 		entry: () => {
 			return {
 				main: entry.server
-			}
+			};
 		},
 
 		output: () => {