SPA mode (#1181)

* rename ssr to respond, since ssr is sometimes false

* add tests to adapter-static

* add failing test for #754

* implement fallback rendering

* render fallback page

* update lockfile

* changeset

* add readme for adapter-static

* formatting

* gah

* missing full stop

* remove ESM export for now, no benefit to it

* windows

* lockfile shenanigans

* argh windows

* ugh WHAT NOW windows

* try this, you dumb timewaster

.changeset/popular-masks-cheat.md

@@ -0,0 +1,6 @@
+---
+'@sveltejs/adapter-static': patch
+'@sveltejs/kit': patch
+---
+
+Prerender fallback page for SPAs

packages/adapter-static/.gitignore

@@ -1,2 +1,4 @@
 .DS_Store
 node_modules
+.svelte
+build

packages/adapter-static/README.md

@@ -1,5 +1,62 @@
-# adapter-static
+# @sveltejs/adapter-static
 
-Adapter for Svelte apps that prerenders your entire site as a collection of static files, which is equivalent to `sapper export`.
+[Adapter](https://kit.svelte.dev/docs#adapters) for SvelteKit apps that prerenders your site as a collection of static files.
 
-This is very experimental. The adapter API is still in flux and will likely change before 1.0.
+```js
+// svelte.config.cjs
+const adapter = require('@sveltejs/adapter-static');
+
+module.exports = {
+	kit: {
+		adapter: adapter({
+			// default options are shown
+			pages: 'build',
+			assets: 'build',
+			fallback: null
+		})
+	}
+};
+```
+
+Unless you're in [SPA mode](#spa-mode), the adapter will attempt to prerender every page of your app, regardless of whether the [`prerender`](https://kit.svelte.dev/docs#ssr-and-javascript-prerender) option is set.
+
+## Options
+
+### pages
+
+The directory to write prerendered pages to. It defaults to `build`.
+
+### assets
+
+The directory to write static assets (the contents of `static`, plus client-side JS and CSS generated by SvelteKit) to. Ordinarily this should be the same as `pages`, and it will default to whatever the value of `pages` is, but in rare circumstances you might need to output pages and assets to separate locations.
+
+### fallback
+
+Specify a fallback page for SPA mode, e.g. `index.html` or `200.html` or `404.html`.
+
+## SPA mode
+
+You can use `adapter-static` to create a single-page app or SPA by specifying a **fallback page**.
+
+> In most situations this is not recommended: it harms SEO, tends to slow down perceived performance, and makes your app inaccessible to users if JavaScript fails or is disabled (which happens [more often than you probably think](https://kryogenix.org/code/browser/everyonehasjs.html)).
+
+The fallback page is a blank HTML page that loads your SvelteKit app and navigates to the correct route. For example [Surge](https://surge.sh/help/adding-a-200-page-for-client-side-routing), a static web host, lets you add a `200.html` file that will handle any requests that don't otherwise match. We can create that file like so:
+
+```js
+// svelte.config.cjs
+const adapter = require('@sveltejs/adapter-static');
+
+module.exports = {
+	kit: {
+		adapter: adapter({
+			fallback: '200.html'
+		})
+	}
+};
+```
+
+When operating in SPA mode, only pages that have the [`prerender`](https://kit.svelte.dev/docs#ssr-and-javascript-prerender) option set will be prerendered.
+
+## License
+
+[MIT](LICENSE)

packages/adapter-static/index.js → packages/adapter-static/index.cjs

@@ -1,4 +1,4 @@
-module.exports = function ({ pages = 'build', assets = 'build' } = {}) {
+module.exports = function ({ pages = 'build', assets = pages, fallback = null } = {}) {
 	/** @type {import('@sveltejs/kit').Adapter} */
 	const adapter = {
 		name: '@sveltejs/adapter-static',
@@ -8,7 +8,8 @@ module.exports = function ({ pages = 'build', assets = 'build' } = {}) {
 			utils.copy_client_files(assets);
 
 			await utils.prerender({
-				force: true,
+				fallback,
+				all: !fallback,
 				dest: pages
 			});
 		}

packages/adapter-static/package.json

@@ -3,11 +3,21 @@
 	"version": "1.0.0-next.4",
 	"scripts": {
 		"lint": "eslint --ignore-path .gitignore \"**/*.{ts,js,svelte}\" && npm run check-format",
+		"check": "tsc",
 		"format": "prettier --write . --config ../../.prettierrc --ignore-path .gitignore",
-		"check-format": "prettier --check . --config ../../.prettierrc --ignore-path .gitignore"
+		"check-format": "prettier --check . --config ../../.prettierrc --ignore-path .gitignore",
+		"test": "uvu test test.js"
 	},
 	"devDependencies": {
 		"@sveltejs/kit": "workspace:*",
-		"typescript": "^4.2.3"
+		"playwright-chromium": "^1.10.0",
+		"port-authority": "^1.1.2",
+		"sirv": "^1.0.11",
+		"typescript": "^4.2.4"
+	},
+	"type": "module",
+	"main": "index.cjs",
+	"exports": {
+		"require": "./index.cjs"
 	}
 }

packages/adapter-static/test/apps/prerendered/.gitignore

@@ -0,0 +1,5 @@
+.DS_Store
+node_modules
+/.svelte
+/build
+/functions

packages/adapter-static/test/apps/prerendered/.npmrc

@@ -0,0 +1 @@
+engine-strict=true

packages/adapter-static/test/apps/prerendered/package.json

@@ -0,0 +1,15 @@
+{
+	"name": "~TODO~",
+	"version": "0.0.1",
+	"scripts": {
+		"dev": "svelte-kit dev",
+		"build": "svelte-kit build",
+		"start": "svelte-kit start"
+	},
+	"devDependencies": {
+		"@sveltejs/kit": "next",
+		"svelte": "^3.29.0",
+		"vite": "^2.1.0"
+	},
+	"type": "module"
+}

packages/adapter-static/test/apps/prerendered/src/app.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<meta name="viewport" content="width=device-width, initial-scale=1" />
+		%svelte.head%
+	</head>
+	<body>
+		<div id="svelte">%svelte.body%</div>
+	</body>
+</html>

packages/adapter-static/test/apps/prerendered/src/global.d.ts

@@ -0,0 +1,3 @@
+/// <reference types="@sveltejs/kit" />
+/// <reference types="svelte" />
+/// <reference types="vite/client" />

packages/adapter-static/test/apps/prerendered/src/routes/index.svelte

@@ -0,0 +1 @@
+<h1>This page was prerendered</h1>

packages/adapter-static/test/apps/prerendered/svelte.config.cjs

@@ -0,0 +1,7 @@
+/** @type {import('@sveltejs/kit').Config} */
+module.exports = {
+	kit: {
+		adapter: require('../../../index.cjs')(),
+		target: '#svelte'
+	}
+};

packages/adapter-static/test/apps/spa/.gitignore

@@ -0,0 +1,5 @@
+.DS_Store
+node_modules
+/.svelte
+/build
+/functions

packages/adapter-static/test/apps/spa/.npmrc

@@ -0,0 +1 @@
+engine-strict=true

packages/adapter-static/test/apps/spa/README.md

@@ -0,0 +1,38 @@
+# create-svelte
+
+Everything you need to build a Svelte project, powered by [`create-svelte`](https://github.com/sveltejs/kit/tree/master/packages/create-svelte);
+
+## Creating a project
+
+If you're seeing this, you've probably already done this step. Congrats!
+
+```bash
+# create a new project in the current directory
+npm init svelte@next
+
+# create a new project in my-app
+npm init svelte@next my-app
+```
+
+> Note: the `@next` is temporary
+
+## Developing
+
+Once you've created a project and installed dependencies with `npm install` (or `pnpm install` or `yarn`), start a development server:
+
+```bash
+npm run dev
+
+# or start the server and open the app in a new browser tab
+npm run dev -- --open
+```
+
+## Building
+
+Before creating a production version of your app, install an [adapter](https://kit.svelte.dev/docs#adapters) for your target environment. Then:
+
+```bash
+npm run build
+```
+
+> You can preview the built app with `npm start`, regardless of whether you installed an adapter. This should _not_ be used to serve your app in production.

packages/adapter-static/test/apps/spa/jsconfig.json

@@ -0,0 +1,9 @@
+{
+	"compilerOptions": {
+		"baseUrl": ".",
+		"paths": {
+			"$lib/*": ["src/lib/*"]
+		}
+	},
+	"include": ["src/**/*.d.ts", "src/**/*.js", "src/**/*.svelte"]
+}

packages/adapter-static/test/apps/spa/package.json

@@ -0,0 +1,16 @@
+{
+	"name": "~TODO~",
+	"version": "0.0.1",
+	"scripts": {
+		"dev": "svelte-kit dev",
+		"build": "svelte-kit build",
+		"start": "svelte-kit start"
+	},
+	"devDependencies": {
+		"@sveltejs/adapter-node": "next",
+		"@sveltejs/kit": "next",
+		"svelte": "^3.29.0",
+		"vite": "^2.1.0"
+	},
+	"type": "module"
+}

packages/adapter-static/test/apps/spa/src/app.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<meta name="viewport" content="width=device-width, initial-scale=1" />
+		%svelte.head%
+	</head>
+	<body>
+		<div id="svelte">%svelte.body%</div>
+	</body>
+</html>

packages/adapter-static/test/apps/spa/src/global.d.ts

@@ -0,0 +1,3 @@
+/// <reference types="@sveltejs/kit" />
+/// <reference types="svelte" />
+/// <reference types="vite/client" />

packages/adapter-static/test/apps/spa/src/routes/$layout.svelte

@@ -0,0 +1,6 @@
+<nav>
+	<a href="/">home</a>
+	<a href="/about">about</a>
+</nav>
+
+<slot></slot>

packages/adapter-static/test/apps/spa/src/routes/about.svelte

@@ -0,0 +1,5 @@
+<script context="module">
+	export const prerender = true;
+</script>
+
+<h1>This page was prerendered</h1>

packages/adapter-static/test/apps/spa/src/routes/index.svelte

@@ -0,0 +1 @@
+<h1>This page was not prerendered</h1>

packages/adapter-static/test/apps/spa/svelte.config.cjs

@@ -0,0 +1,9 @@
+/** @type {import('@sveltejs/kit').Config} */
+module.exports = {
+	kit: {
+		adapter: require('../../../index.cjs')({
+			fallback: '200.html'
+		}),
+		target: '#svelte'
+	}
+};

packages/adapter-static/test/test.js

@@ -0,0 +1,33 @@
+import fs from 'fs';
+import * as assert from 'uvu/assert';
+import { run } from './utils.js';
+
+run('prerendered', (test) => {
+	test('generates HTML files', ({ cwd }) => {
+		assert.ok(fs.existsSync(`${cwd}/build/index.html`));
+	});
+
+	test('prerenders content', async ({ base, page }) => {
+		await page.goto(base);
+		assert.equal(await page.textContent('h1'), 'This page was prerendered');
+	});
+});
+
+run('spa', (test) => {
+	test('generates a fallback page', ({ cwd }) => {
+		assert.ok(fs.existsSync(`${cwd}/build/200.html`));
+	});
+
+	test('does not prerender pages without prerender=true', ({ cwd }) => {
+		assert.ok(!fs.existsSync(`${cwd}/build/index.html`));
+	});
+
+	test('prerenders page with prerender=true', ({ cwd }) => {
+		assert.ok(fs.existsSync(`${cwd}/build/about/index.html`));
+	});
+
+	test('renders content in fallback page when JS runs', async ({ base, page }) => {
+		await page.goto(base);
+		assert.equal(await page.textContent('h1'), 'This page was not prerendered');
+	});
+});