Adding blank page for fallback (#1441)

* Adding blank page for fallback

* switching fallback to 200.html

* adding tests

* bug fix

* fixing tests

* Apply suggestions from code review

Co-authored-by: Leah <github.leah@hrmny.sh>

Co-authored-by: Jason Miller <developit@users.noreply.github.com>
Co-authored-by: Leah <github.leah@hrmny.sh>

packages/cli/lib/lib/webpack/render-html-plugin.js

@@ -9,6 +9,8 @@ const { warn } = require('../../util');
 const { info } = require('../../util');
 const { PRERENDER_DATA_FILE_NAME } = require('../constants');
 
+const PREACT_FALLBACK_URL = '/200.html';
+
 let defaultTemplate = resolve(__dirname, '../../resources/template.html');
 
 function read(path) {
@@ -53,10 +55,14 @@ module.exports = async function (config) {
 		writeFileSync(template, content);
 	}
 
-	const htmlWebpackConfig = values => {
+	const htmlWebpackConfig = (values) => {
 		const { url, title, ...routeData } = values;
+		// Do not create a folder if the url is for a specific file.
+		const filename = url.endsWith('.html')
+			? resolve(dest, url.substring(1))
+			: resolve(dest, url.substring(1), 'index.html');
 		return Object.assign(values, {
-			filename: resolve(dest, url.substring(1), 'index.html'),
+			filename,
 			template: `!!ejs-loader?esModule=false!${template}`,
 			minify: isProd && {
 				collapseWhitespace: true,
@@ -90,7 +96,9 @@ module.exports = async function (config) {
 			config,
 			url,
 			ssr() {
-				return config.prerender ? prerender({ cwd, dest, src }, values) : '';
+				return config.prerender && url !== PREACT_FALLBACK_URL
+					? prerender({ cwd, dest, src }, values)
+					: '';
 			},
 			scriptLoading: 'defer',
 			CLI_DATA: { preRenderData: { url, ...routeData } },
@@ -137,12 +145,21 @@ module.exports = async function (config) {
 			);
 		}
 	}
+	/**
+	 * We cache a non SSRed page in service worker so that there is
+	 * no flash of content when user lands on routes other than `/`.
+	 * And we dont have to cache every single html file.
+	 * Go easy on network usage of clients.
+	 */
+	!pages.find((page) => page.url === PREACT_FALLBACK_URL) &&
+		pages.push({ url: PREACT_FALLBACK_URL });
 
-	return pages
+	const resultPages = pages
 		.map(htmlWebpackConfig)
-		.map(conf => new HtmlWebpackPlugin(conf))
+		.map((conf) => new HtmlWebpackPlugin(conf))
 		.concat([new HtmlWebpackExcludeAssetsPlugin()])
-		.concat([...pages.map(page => new PrerenderDataExtractPlugin(page))]);
+		.concat([...pages.map((page) => new PrerenderDataExtractPlugin(page))]);
+	return resultPages;
 };
 
 // Adds a preact_prerender_data in every folder so that the data could be fetched separately.
@@ -154,7 +171,11 @@ class PrerenderDataExtractPlugin {
 		this.data_ = JSON.stringify(cliData.preRenderData || {});
 	}
 	apply(compiler) {
-		compiler.hooks.emit.tap('PrerenderDataExtractPlugin', compilation => {
+		compiler.hooks.emit.tap('PrerenderDataExtractPlugin', (compilation) => {
+			if (this.location_ === `${PREACT_FALLBACK_URL}/`) {
+				// We dont build prerender data for `200.html`. It can re-use the one for homepage.
+				return;
+			}
 			let path = this.location_ + PRERENDER_DATA_FILE_NAME;
 			if (path.startsWith('/')) {
 				path = path.substr(1);
@@ -166,3 +187,5 @@ class PrerenderDataExtractPlugin {
 		});
 	}
 }
+
+exports.PREACT_FALLBACK_URL = PREACT_FALLBACK_URL;

packages/cli/lib/lib/webpack/webpack-client-config.js

@@ -228,7 +228,7 @@ function isProd(config) {
 				swSrc: swPath,
 				swDest: 'sw-esm.js',
 				include: [
-					/^\/?index\.html$/,
+					/200\.html$/,
 					/\.esm.js$/,
 					/\.css$/,
 					/\.(png|jpg|svg|gif|webp)$/,
@@ -246,12 +246,7 @@ function isProd(config) {
 		prodConfig.plugins.push(
 			new InjectManifest({
 				swSrc: swPath,
-				include: [
-					/index\.html$/,
-					/\.js$/,
-					/\.css$/,
-					/\.(png|jpg|svg|gif|webp)$/,
-				],
+				include: [/200\.html$/, /\.js$/, /\.css$/, /\.(png|jpg|svg|gif|webp)$/],
 				exclude: [/\.esm\.js$/],
 			})
 		);

packages/cli/package.json

@@ -58,7 +58,7 @@
 		"preact": "^10.0.0",
 		"preact-render-to-string": "^5.0.6",
 		"preact-router": "^3.0.1",
-		"puppeteer": "^5.0.0",
+		"puppeteer": "^5.3.1",
 		"sass-loader": "^10.0.4",
 		"shelljs": "^0.8.3",
 		"sirv": "^1.0.0-next.2"

packages/cli/sw/index.js

@@ -20,7 +20,7 @@ export function setupRouting() {
 
 	setCatchHandler(({ event }) => {
 		if (isNav(event)) {
-			return caches.match(getCacheKeyForURL('/index.html'));
+			return caches.match(getCacheKeyForURL('/200.html'));
 		}
 		return Response.error();
 	});

packages/cli/tests/images/build.js

@@ -16,6 +16,7 @@ exports.default = exports.full = Object.assign({}, common, {
 	'bundle.7e56a.css': 901,
 	'favicon.ico': 15086,
 	'index.html': 2034,
+	'200.html': 613,
 	'manifest.json': 455,
 	'preact_prerender_data.json': 11,
 	'push-manifest.json': 812,

packages/cli/tests/service-worker.test.js

@@ -5,12 +5,26 @@ const { sleep } = require('./lib/utils');
 const { getServer } = require('./server');
 const startChrome = require('./lib/chrome');
 
+async function enableOfflineMode(page, browser) {
+	await sleep(2000); // wait for service worker installation.
+	await page.setOfflineMode(true);
+	const targets = await browser.targets();
+	const serviceWorker = targets.find((t) => t.type() === 'service_worker');
+	const serviceWorkerConnection = await serviceWorker.createCDPSession();
+	await serviceWorkerConnection.send('Network.enable');
+	await serviceWorkerConnection.send('Network.emulateNetworkConditions', {
+		offline: true,
+		latency: 0,
+		downloadThroughput: 0,
+		uploadThroughput: 0,
+	});
+}
+
 describe('preact service worker tests', () => {
 	let server, browser, dir;
 
 	beforeAll(async () => {
 		dir = await create('default');
-		browser = await startChrome();
 		await build(dir, {
 			sw: true,
 			esm: true,
@@ -19,9 +33,16 @@ describe('preact service worker tests', () => {
 		server = getServer(dir);
 	});
 
+	beforeEach(async () => {
+		browser = await startChrome();
+	});
+
+	afterEach(async () => {
+		await browser.close();
+	});
+
 	afterAll(async () => {
 		await server.server.stop();
-		await browser.close();
 	});
 
 	it('works offline', async () => {
@@ -31,15 +52,14 @@ describe('preact service worker tests', () => {
 			waitUntil: 'networkidle0',
 		});
 		const initialContent = await page.content();
-		await sleep(2000); // wait for service worker installation.
-		await page.setOfflineMode(true);
-		await page.reload();
+		await enableOfflineMode(page, browser);
+		await page.reload({ waitUntil: 'networkidle0' });
 		const offlineContent = await page.content();
 		await page.waitForSelector('h1');
 		expect(
-			await page.$$eval('h1', nodes => nodes.map(n => n.innerText))
+			await page.$$eval('h1', (nodes) => nodes.map((n) => n.innerText))
 		).toEqual(['Preact App', 'Home']);
-		expect(offlineContent).toEqual(initialContent);
+		expect(offlineContent).not.toEqual(initialContent);
 	});
 
 	it('should fetch navigation requests with networkFirst', async () => {
@@ -64,4 +84,26 @@ describe('preact service worker tests', () => {
 		expect(initialContent).not.toEqual(refreshedContent);
 		expect(refreshedContent.includes(NEW_TITLE)).toEqual(true);
 	});
+
+	it('should respond with 200.html when offline', async () => {
+		const swText = await fetch('http://localhost:3000/sw-esm.js').then((res) =>
+			res.text()
+		);
+		// eslint-disable-next-line no-useless-escape
+		expect(swText).toContain(
+			'caches.match((t="/200.html",ce().getCacheKeyForURL(t)))'
+		);
+		const page = await browser.newPage();
+		await page.setCacheEnabled(false);
+		await page.goto('http://localhost:3000', {
+			waitUntil: 'networkidle0',
+		});
+		await enableOfflineMode(page, browser);
+		await page.reload({ waitUntil: 'networkidle0' });
+		expect(
+			await page.$$eval('script[type=__PREACT_CLI_DATA__]', (nodes) =>
+				nodes.map((n) => n.innerText)
+			)
+		).toEqual(['%7B%22preRenderData%22:%7B%22url%22:%22/200.html%22%7D%7D']);
+	});
 });

yarn.lock

@@ -5343,10 +5343,10 @@ detect-node@^2.0.4:
   resolved "https://registry.yarnpkg.com/detect-node/-/detect-node-2.0.4.tgz#014ee8f8f669c5c58023da64b8179c083a28c46c"
   integrity sha512-ZIzRpLJrOj7jjP2miAtgqIfmzbxa4ZOr5jJc601zklsfEx9oTzmmj2nVpIPRpNlRTIh8lc1kyViIY7BWSGNmKw==
 
-devtools-protocol@0.0.781568:
-  version "0.0.781568"
-  resolved "https://registry.yarnpkg.com/devtools-protocol/-/devtools-protocol-0.0.781568.tgz#4cdca90a952d2c77831096ff6cd32695d8715a04"
-  integrity sha512-9Uqnzy6m6zEStluH9iyJ3iHyaQziFnMnLeC8vK0eN6smiJmIx7+yB64d67C2lH/LZra+5cGscJAJsNXO+MdPMg==
+devtools-protocol@0.0.799653:
+  version "0.0.799653"
+  resolved "https://registry.yarnpkg.com/devtools-protocol/-/devtools-protocol-0.0.799653.tgz#86fc95ce5bf4fdf4b77a58047ba9d2301078f119"
+  integrity sha512-t1CcaZbvm8pOlikqrsIM9GOa7Ipp07+4h/q9u0JXBWjPCjHdBl9KkddX87Vv9vBHoBGtwV79sYQNGnQM6iS5gg==
 
 dezalgo@^1.0.0, dezalgo@~1.0.3:
   version "1.0.3"
@@ -9618,7 +9618,7 @@ mime@1.6.0:
   resolved "https://registry.yarnpkg.com/mime/-/mime-1.6.0.tgz#32cd9e5c64553bd58d19a568af452acff04981b1"
   integrity sha512-x0Vn8spI+wuJ1O6S7gnbaQg8Pxh4NNHb7KSINmEWKiPE4RKOplvijn+NkmYmmRgP68mc70j2EbeTFRsrswaQeg==
 
-mime@^2.0.3, mime@^2.3.1, mime@^2.4.4:
+mime@^2.3.1, mime@^2.4.4:
   version "2.4.6"
   resolved "https://registry.yarnpkg.com/mime/-/mime-2.4.6.tgz#e5b407c90db442f2beb5b162373d07b69affa4d1"
   integrity sha512-RZKhC3EmpBchfTGBVb8fb+RL2cWyw/32lshnsETttkBAyAUXSGHxbEJWWRXc751DrIxG1q04b8QwMbAwkRPpUA==
@@ -11801,16 +11801,15 @@ pupa@^2.0.1:
   dependencies:
     escape-goat "^2.0.0"
 
-puppeteer@^5.0.0:
-  version "5.2.1"
-  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-5.2.1.tgz#7f0564f0a5384f352a38c8cc42af875cd87f4ea6"
-  integrity sha512-PZoZG7u+T6N1GFWBQmGVG162Ak5MAy8nYSVpeeQrwJK2oYUlDWpHEJPcd/zopyuEMTv7DiztS1blgny1txR2qw==
+puppeteer@^5.3.1:
+  version "5.3.1"
+  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-5.3.1.tgz#324e190d89f25ac33dba539f57b82a18553f8646"
+  integrity sha512-YTM1RaBeYrj6n7IlRXRYLqJHF+GM7tasbvrNFx6w1S16G76NrPq7oYFKLDO+BQsXNtS8kW2GxWCXjIMPvfDyaQ==
   dependencies:
     debug "^4.1.0"
-    devtools-protocol "0.0.781568"
+    devtools-protocol "0.0.799653"
     extract-zip "^2.0.0"
     https-proxy-agent "^4.0.0"
-    mime "^2.0.3"
     pkg-dir "^4.2.0"
     progress "^2.0.1"
     proxy-from-env "^1.0.0"