Preventing form defaults. Fixes #294.

Downgrade node-sass (fixes #319)

.babelrc

@@ -1,13 +0,0 @@
-{
-  "plugins": [
-    "transform-class-properties",
-    "transform-react-constant-elements",
-    "transform-react-remove-prop-types",
-    [
-      "transform-react-jsx",
-      {
-        "pragma": "h"
-      }
-    ]
-  ]
-}

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,36 @@
+---
+name: Bug report
+about: Something is not working as expected
+labels: 
+
+---
+
+**Before you start**
+Please take a look at the [FAQ](https://github.com/GoogleChromeLabs/squoosh/wiki/FAQ) as well as the already opened issues! If nothing fits your problem, go ahead and fill out the following template:
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Version:**
+ - OS w/ version: [e.g. iOS 12]
+ - Browser w/ version [e.g. Chrome 70]
+ - Node version: [e.g. 10.11.0]
+ - npm version: [e.g. 6.4.1]
+
+**Is your issue related to the quality of image compression?**
+Please attach original and output images (you can drag & drop to attach). 
+- Original image 
+- Output image from Squoosh
+
+**Additional context, screenshots, screencasts**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,18 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+labels: 
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Does other service/app have this feature?**
+Add any service you know/use that has this feature (We want to know for research)
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.travis.yml

@@ -1,5 +1,7 @@
 language: node_js
 node_js:
 - node
+- 10
+- 8
 cache: npm
 script: npm run build || npm run build # scss ts definitions need to be generated before an actual build

README.md

@@ -1,5 +1,34 @@
-# Squoosh!
+# [Squoosh]!
 
-Squoosh will be an image compression web app that allows you to dive into the
+[Squoosh] is an image compression web app that allows you to dive into the advanced options provided
-advanced options provided by various image compressors.
+by various image compressors.
 
+# Privacy
+
+Google Analytics is used to record the following:
+
+* [Basic visit data](https://support.google.com/analytics/answer/6004245?ref_topic=2919631).
+* Before and after image size once an image is downloaded. These values are rounded to the nearest
+  kilobyte.
+
+Image compression is handled locally; no additional data is sent to the server.
+
+# Building locally
+
+Clone the repo, and:
+
+```sh
+npm install
+npm run build
+```
+
+You'll get an error on first build because of [a stupid bug we haven't fixed
+yet](https://github.com/GoogleChromeLabs/squoosh/issues/251).
+
+You can run the development server with:
+
+```sh
+npm start
+```
+
+[Squoosh]: https://squoosh.app

_headers.ejs

@@ -0,0 +1,18 @@
+# Long-term cache by default.
+/*
+  Cache-Control: max-age=31536000
+
+# And here are the exceptions:
+/
+  Cache-Control: no-cache
+
+/serviceworker.js
+  Cache-Control: no-cache
+
+/manifest.json
+  Cache-Control: must-revalidate, max-age=3600
+
+# URLs in /assets do not include a hash and are mutable.
+# But it isn't a big deal if the user gets an old version.
+/assets/*
+  Cache-Control: must-revalidate, max-age=3600

codecs/README.md

@@ -11,6 +11,6 @@ $ npm install
 $ npm run build
 ```
 
-This will build two files: `<codec name>_<enc or dec>.js` and `<codec name>_<enc or dec>.wasm`. It will most likely be necessary to set [`Module["locateFile"]`](https://kripken.github.io/emscripten-site/docs/api_reference/module.html#affecting-execution) to sucessfully load the `.wasm` file. When the `.js` file is loaded, a global `<codec name>_<enc or dec>` is created with the same API as an [Emscripten `Module`](https://kripken.github.io/emscripten-site/docs/api_reference/module.html).
+This will build two files: `<codec name>_<enc or dec>.js` and `<codec name>_<enc or dec>.wasm`. It will most likely be necessary to set [`Module["locateFile"]`](https://kripken.github.io/emscripten-site/docs/api_reference/module.html#affecting-execution) to successfully load the `.wasm` file. When the `.js` file is loaded, a global `<codec name>_<enc or dec>` is created with the same API as an [Emscripten `Module`](https://kripken.github.io/emscripten-site/docs/api_reference/module.html).
 
 Each codec will document its API in its README.

config/asset-template-plugin.js

@@ -0,0 +1,47 @@
+const path = require('path');
+const fs = require('fs');
+const ejs = require('ejs');
+const AssetsPlugin = require('assets-webpack-plugin');
+
+module.exports = class AssetTemplatePlugin extends AssetsPlugin {
+  constructor(options) {
+    options = options || {};
+    if (!options.template) throw Error('AssetTemplatePlugin: template option is required.');
+    super({
+      useCompilerPath: true,
+      filename: options.filename,
+      processOutput: files => this._processOutput(files)
+    });
+    this._template = path.resolve(process.cwd(), options.template);
+    const ignore = options.ignore || /(manifest\.json|\.DS_Store)$/;
+    this._ignore = typeof ignore === 'function' ? ({ test: ignore }) : ignore;
+  }
+
+  _processOutput(files) {
+    const mapping = {
+      all: [],
+      byType: {},
+      entries: {}
+    };
+    for (const entryName in files) {
+      // non-entry-point-derived assets are collected under an empty string key
+      // since that's a bit awkward, we'll call them "assets"
+      const name = entryName === '' ? 'assets' : entryName;
+      const listing = files[entryName];
+      const entry = mapping.entries[name] = {
+        all: [],
+        byType: {}
+      };
+      for (let type in listing) {
+        const list = [].concat(listing[type]).filter(file => !this._ignore.test(file));
+        if (!list.length) continue;
+        mapping.all = mapping.all.concat(list);
+        mapping.byType[type] = (mapping.byType[type] || []).concat(list);
+        entry.all = entry.all.concat(list);
+        entry.byType[type] = (entry.byType[type] || []).concat(list);
+      }
+    }
+    mapping.files = mapping.all;
+    return ejs.render(fs.readFileSync(this._template, 'utf8'), mapping);
+  }
+};

config/auto-sw-plugin.js

@@ -0,0 +1,158 @@
+const util = require('util');
+const minimatch = require('minimatch');
+const SingleEntryPlugin = require('webpack/lib/SingleEntryPlugin');
+const WebWorkerTemplatePlugin = require('webpack/lib/webworker/WebWorkerTemplatePlugin');
+const ParserHelpers = require('webpack/lib/ParserHelpers');
+
+const NAME = 'auto-sw-plugin';
+const JS_TYPES = ['auto', 'esm', 'dynamic'];
+
+/**
+ * Automatically finds and bundles Service Workers by looking for navigator.serviceWorker.register(..).
+ * An Array of webpack assets is injected into the Service Worker bundle as a `BUILD_ASSETS` global.
+ * Hidden and `.map` files are excluded by default, and this can be customized using the include & exclude options.
+ * @example
+ *  // webpack config
+ *  plugins: [
+ *    new AutoSWPlugin({
+ *      exclude: [
+ *        '**\/.*',     // don't expose hidden files (default)
+ *        '**\/*.map',  // don't precache sourcemaps (default)
+ *        'index.html'  // don't cache the page itself
+ *      ]
+ *    })
+ *  ]
+ * @param {Object} [options={}]
+ * @param {string[]} [options.exclude]  Minimatch pattern(s) of which assets to omit from BUILD_ASSETS.
+ * @param {string[]} [options.include]  Minimatch pattern(s) of assets to allow in BUILD_ASSETS.
+ */
+module.exports = class AutoSWPlugin {
+  constructor(options) {
+    this.options = Object.assign({
+      exclude: [
+        '**/*.map',
+        '**/.*'
+      ]
+    }, options || {});
+  }
+
+  apply(compiler) {
+    const serviceWorkers = [];
+
+    compiler.hooks.emit.tapPromise(NAME, compilation => this.emit(compiler, compilation, serviceWorkers));
+
+    compiler.hooks.normalModuleFactory.tap(NAME, (factory) => {
+      for (const type of JS_TYPES) {
+        factory.hooks.parser.for(`javascript/${type}`).tap(NAME, parser => {
+          let counter = 0;
+
+          const processRegisterCall = expr => {
+            const dep = parser.evaluateExpression(expr.arguments[0]);
+
+            if (!dep.isString()) {
+              parser.state.module.warnings.push({
+                message: 'navigator.serviceWorker.register() will only be bundled if passed a String literal.'
+              });
+              return false;
+            }
+
+            const filename = dep.string;
+            const outputFilename = this.options.filename || 'serviceworker.js'
+            const context = parser.state.current.context;
+            serviceWorkers.push({
+              outputFilename,
+              filename,
+              context
+            });
+
+            const id = `__webpack__serviceworker__${++counter}`;
+            ParserHelpers.toConstantDependency(parser, id)(expr.arguments[0]);
+            return ParserHelpers.addParsedVariableToModule(parser, id, '__webpack_public_path__ + ' + JSON.stringify(outputFilename));
+          };
+
+          parser.hooks.call.for('navigator.serviceWorker.register').tap(NAME, processRegisterCall);
+          parser.hooks.call.for('self.navigator.serviceWorker.register').tap(NAME, processRegisterCall);
+          parser.hooks.call.for('window.navigator.serviceWorker.register').tap(NAME, processRegisterCall);
+        });
+      }
+    });
+  }
+
+  createFilter(list) {
+    const filters = [].concat(list);
+    for (let i=0; i<filters.length; i++) {
+      if (typeof filters[i] === 'string') {
+        filters[i] = minimatch.filter(filters[i]);
+      }
+    }
+    return filters;
+  }
+
+  async emit(compiler, compilation, serviceWorkers) {
+    let assetMapping = Object.keys(compilation.assets);
+    if (this.options.include) {
+      const filters = this.createFilter(this.options.include);
+      assetMapping = assetMapping.filter(filename => {
+        for (const filter of filters) {
+          if (filter(filename)) return true;
+        }
+        return false;
+      });
+    }
+    if (this.options.exclude) {
+      const filters = this.createFilter(this.options.exclude);
+      assetMapping = assetMapping.filter(filename => {
+        for (const filter of filters) {
+          if (filter(filename)) return false;
+        }
+        return true;
+      });
+    }
+    await Promise.all(serviceWorkers.map(
+      (serviceWorker, index) => this.compileServiceWorker(compiler, compilation, serviceWorker, index, assetMapping)
+    ));
+  }
+
+  async compileServiceWorker(compiler, compilation, options, index, assetMapping) {
+    const entryFilename = options.filename;
+
+    const chunkFilename = compiler.options.output.chunkFilename.replace(/\.([a-z]+)$/i, '.serviceworker.$1');
+    const workerOptions = {
+      filename: options.outputFilename, // chunkFilename.replace(/\.?\[(?:chunkhash|contenthash|hash)(:\d+(?::\d+)?)?\]/g, ''),
+      chunkFilename: this.options.chunkFilename || chunkFilename,
+      globalObject: 'self'
+    };
+
+    const childCompiler = compilation.createChildCompiler(NAME, { filename: workerOptions.filename });
+    (new WebWorkerTemplatePlugin(workerOptions)).apply(childCompiler);
+
+    /* The duplication DefinePlugin ends up causing is problematic (it doesn't hoist injections), so we'll do it manually. */
+    // (new DefinePlugin({
+    //   BUILD_ASSETS: JSON.stringify(assetMapping)
+    // })).apply(childCompiler);
+    (new SingleEntryPlugin(options.context, entryFilename, workerOptions.filename)).apply(childCompiler);
+
+    const subCache = `subcache ${__dirname} ${entryFilename} ${index}`;
+    let childCompilation;
+    childCompiler.hooks.compilation.tap(NAME, c => {
+      childCompilation = c;
+      if (childCompilation.cache) {
+        if (!childCompilation.cache[subCache]) childCompilation.cache[subCache] = {};
+        childCompilation.cache = childCompilation.cache[subCache];
+      }
+    });
+
+    await (util.promisify(childCompiler.runAsChild.bind(childCompiler)))();
+
+    const versionVar = this.options.version ?
+      `var VERSION = ${JSON.stringify(this.options.version)};` : '';
+    const original = childCompilation.assets[workerOptions.filename].source();
+    const source = `${versionVar}var BUILD_ASSETS=${JSON.stringify(assetMapping)};${original}`;
+    childCompilation.assets[workerOptions.filename] = {
+      source: () => source,
+      size: () => Buffer.byteLength(source, 'utf8')
+    };
+
+    Object.assign(compilation.assets, childCompilation.assets);
+  }
+};

global.d.ts

@@ -1,16 +1,21 @@
 declare const __webpack_public_path__: string;
+declare const PRERENDER: boolean;
 
 declare interface NodeModule {
   hot: any;
 }
 
 declare interface Window {
-  STATE: any
+  STATE: any;
+  ga: typeof ga;
 }
 
 declare namespace JSX {
   interface Element { }
   interface IntrinsicElements { }
+  interface HTMLAttributes {
+    decoding?: string;
+  }
 }
 
 declare module 'classnames' {

package.json

@@ -1,13 +1,13 @@
 {
   "private": true,
   "name": "squoosh",
-  "version": "0.0.0",
+  "version": "1.0.2",
   "license": "apache-2.0",
   "scripts": {
-    "start": "webpack serve --host 0.0.0.0 --hot",
+    "start": "webpack-dev-server --host 0.0.0.0 --hot",
     "build": "webpack -p",
-    "lint": "tslint -c tslint.json -t verbose 'src/**/*.{ts,tsx,js,jsx}'",
+    "lint": "tslint -c tslint.json  -p tsconfig.json -t verbose 'src/**/*.{ts,tsx,js,jsx}'",
-    "lintfix": "tslint -c tslint.json -t verbose --fix 'src/**/*.{ts,tsx,js,jsx}'"
+    "lintfix": "tslint -c tslint.json -p tsconfig.json -t verbose --fix 'src/**/*.{ts,tsx,js,jsx}'"
   },
   "husky": {
     "hooks": {
@@ -15,58 +15,55 @@
     }
   },
   "devDependencies": {
-    "@types/node": "^9.6.35",
+    "@types/node": "^10.12.6",
     "@types/pretty-bytes": "^5.1.0",
     "@types/webassembly-js-api": "0.0.1",
     "@webcomponents/custom-elements": "^1.2.1",
-    "babel-loader": "^7.1.5",
+    "@webpack-cli/serve": "^0.1.2",
-    "babel-plugin-jsx-pragmatic": "^1.0.2",
+    "assets-webpack-plugin": "^3.9.7",
-    "babel-plugin-syntax-dynamic-import": "^6.18.0",
-    "babel-plugin-transform-class-properties": "^6.24.1",
-    "babel-plugin-transform-decorators-legacy": "^1.3.5",
-    "babel-plugin-transform-object-rest-spread": "^6.26.0",
-    "babel-plugin-transform-react-constant-elements": "^6.23.0",
-    "babel-plugin-transform-react-jsx": "^6.24.1",
-    "babel-plugin-transform-react-remove-prop-types": "^0.4.19",
-    "babel-preset-env": "^1.7.0",
-    "babel-register": "^6.26.0",
     "classnames": "^2.2.6",
-    "clean-webpack-plugin": "^0.1.19",
+    "clean-webpack-plugin": "^1.0.0",
     "comlink": "^3.0.3",
-    "copy-webpack-plugin": "^4.5.3",
+    "copy-webpack-plugin": "^4.6.0",
-    "css-loader": "^0.28.11",
+    "critters-webpack-plugin": "^2.0.1",
+    "css-loader": "^1.0.1",
+    "ejs": "^2.6.1",
     "exports-loader": "^0.7.0",
-    "file-drop-element": "0.0.7",
+    "file-drop-element": "^0.0.9",
-    "file-loader": "^1.1.11",
+    "file-loader": "^2.0.0",
     "html-webpack-plugin": "^3.2.0",
-    "husky": "^1.1.2",
+    "husky": "^1.1.4",
+    "idb-keyval": "^3.1.0",
     "if-env": "^1.0.4",
     "linkstate": "^1.1.1",
     "loader-utils": "^1.1.0",
-    "mini-css-extract-plugin": "^0.3.0",
+    "mini-css-extract-plugin": "^0.4.4",
-    "node-sass": "^4.9.4",
+    "minimatch": "^3.0.4",
-    "optimize-css-assets-webpack-plugin": "^4.0.3",
+    "node-sass": "^4.9.0",
+    "optimize-css-assets-webpack-plugin": "^5.0.1",
     "pointer-tracker": "^2.0.3",
     "preact": "^8.3.1",
+    "prerender-loader": "^1.2.0",
     "pretty-bytes": "^5.1.0",
     "progress-bar-webpack-plugin": "^1.11.0",
     "raw-loader": "^0.5.1",
     "sass-loader": "^7.1.0",
-    "script-ext-html-webpack-plugin": "^2.0.1",
+    "script-ext-html-webpack-plugin": "^2.1.3",
-    "source-map-loader": "^0.2.3",
+    "source-map-loader": "^0.2.4",
-    "style-loader": "^0.22.1",
+    "style-loader": "^0.23.1",
-    "ts-loader": "^4.4.2",
+    "terser-webpack-plugin": "^1.1.0",
+    "ts-loader": "^5.3.0",
     "tslint": "^5.11.0",
-    "tslint-config-airbnb": "^5.9.2",
+    "tslint-config-airbnb": "^5.11.0",
     "tslint-config-semistandard": "^7.0.0",
     "tslint-react": "^3.6.0",
-    "typescript": "^2.9.2",
+    "typescript": "^3.1.6",
     "typings-for-css-modules-loader": "^1.7.0",
-    "webpack": "=4.19.1",
+    "url-loader": "^1.1.2",
-    "webpack-bundle-analyzer": "^2.13.1",
+    "webpack": "^4.25.1",
-    "webpack-cli": "^2.1.5",
+    "webpack-bundle-analyzer": "^3.0.3",
-    "webpack-dev-server": "^3.1.5",
+    "webpack-cli": "^3.1.2",
-    "webpack-plugin-replace": "^1.1.1",
+    "webpack-dev-server": "^3.1.10",
     "worker-plugin": "^1.1.1"
   }
 }

src/codecs/decoders.ts

@@ -1,9 +1,8 @@
 import { nativeDecode, sniffMimeType, canDecodeImage } from '../lib/util';
 import Processor from './processor';
+import webpDataUrl from 'url-loader!./tiny.webp';
 
-// tslint:disable-next-line:max-line-length It’s a data URL. Whatcha gonna do?
+const nativeWebPSupported = canDecodeImage(webpDataUrl);
-const webpFile = 'data:image/webp;base64,UklGRh4AAABXRUJQVlA4TBEAAAAvAAAAAAfQ//73v/+BiOh/AAA=';
-const nativeWebPSupported = canDecodeImage(webpFile);
 
 export async function decodeImage(blob: Blob, processor: Processor): Promise<ImageData> {
   const mimeType = await sniffMimeType(blob);

src/codecs/imagequant/options.tsx

@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldValueAsNumber, konami } from '../../lib/util';
+import { inputFieldValueAsNumber, konami, preventDefault } from '../../lib/util';
 import { QuantizeOptions } from './processor-meta';
 import * as style from '../../components/Options/style.scss';
 import Expander from '../../components/expander';
@@ -42,7 +42,7 @@ export default class QuantizerOptions extends Component<Props, State> {
 
   render({ options }: Props, { extendedSettings }: State) {
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <Expander>
           {extendedSettings ?
             <label class={style.optionTextFirst}>

src/codecs/mozjpeg/options.tsx

@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldChecked, inputFieldValueAsNumber } from '../../lib/util';
+import { inputFieldChecked, inputFieldValueAsNumber, preventDefault } from '../../lib/util';
 import { EncodeOptions, MozJpegColorSpace } from './encoder-meta';
 import * as style from '../../components/Options/style.scss';
 import Checkbox from '../../components/checkbox';
@@ -58,7 +58,7 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
     // I'm rendering both lossy and lossless forms, as it becomes much easier when
     // gathering the data.
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <div class={style.optionOneCell}>
           <Range
             name="quality"

src/codecs/optipng/options.tsx

@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldValueAsNumber } from '../../lib/util';
+import { inputFieldValueAsNumber, preventDefault } from '../../lib/util';
 import { EncodeOptions } from './encoder-meta';
 import Range from '../../components/range';
 import * as style from '../../components/Options/style.scss';
@@ -23,7 +23,7 @@ export default class OptiPNGEncoderOptions extends Component<Props, {}> {
 
   render({ options }: Props) {
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <div class={style.optionOneCell}>
           <Range
             name="level"

src/codecs/processor-worker.ts

@@ -7,31 +7,46 @@ import { EncodeOptions as WebPEncoderOptions } from './webp/encoder-meta';
 async function mozjpegEncode(
   data: ImageData, options: MozJPEGEncoderOptions,
 ): Promise<ArrayBuffer> {
-  const { encode } = await import('./mozjpeg/encoder');
+  const { encode } = await import(
+    /* webpackChunkName: "process-mozjpeg-enc" */
+    './mozjpeg/encoder',
+  );
   return encode(data, options);
 }
 
 async function quantize(data: ImageData, opts: QuantizeOptions): Promise<ImageData> {
-  const { process } = await import('./imagequant/processor');
+  const { process } = await import(
+    /* webpackChunkName: "process-imagequant" */
+    './imagequant/processor',
+  );
   return process(data, opts);
 }
 
 async function optiPngEncode(
   data: BufferSource, options: OptiPNGEncoderOptions,
 ): Promise<ArrayBuffer> {
-  const { compress } = await import('./optipng/encoder');
+  const { compress } = await import(
+    /* webpackChunkName: "process-optipng" */
+    './optipng/encoder',
+  );
   return compress(data, options);
 }
 
 async function webpEncode(
   data: ImageData, options: WebPEncoderOptions,
 ): Promise<ArrayBuffer> {
-  const { encode } = await import('./webp/encoder');
+  const { encode } = await import(
+    /* webpackChunkName: "process-webp-enc" */
+    './webp/encoder',
+  );
   return encode(data, options);
 }
 
 async function webpDecode(data: ArrayBuffer): Promise<ImageData> {
-  const { decode } = await import('./webp/decoder');
+  const { decode } = await import(
+    /* webpackChunkName: "process-webp-dec" */
+    './webp/decoder',
+  );
   return decode(data);
 }
 

src/codecs/processor.ts

@@ -61,7 +61,10 @@ export default class Processor {
           // worker-loader does magic here.
           // @ts-ignore - Typescript doesn't know about the 2nd param to new Worker, and the
           // definition can't be overwritten.
-          this._worker = new Worker('./processor-worker.ts', { type: 'module' }) as Worker;
+          this._worker = new Worker(
+            './processor-worker.ts',
+            { name: 'processor-worker', type: 'module' },
+          ) as Worker;
           // Need to do some TypeScript trickery to make the type match.
           this._workerApi = proxy(this._worker) as any as ProcessorWorkerApi;
         }

src/codecs/resize/options.tsx

@@ -1,7 +1,7 @@
 import { h, Component } from 'preact';
 import linkState from 'linkstate';
 import { bind, linkRef } from '../../lib/initial-util';
-import { inputFieldValueAsNumber, inputFieldValue } from '../../lib/util';
+import { inputFieldValueAsNumber, inputFieldValue, preventDefault } from '../../lib/util';
 import { ResizeOptions } from './processor-meta';
 import * as style from '../../components/Options/style.scss';
 import Checkbox from '../../components/checkbox';
@@ -78,7 +78,7 @@ export default class ResizerOptions extends Component<Props, State> {
 
   render({ options, isVector }: Props, { maintainAspect }: State) {
     return (
-      <form ref={linkRef(this, 'form')} class={style.optionsSection}>
+      <form ref={linkRef(this, 'form')} class={style.optionsSection} onSubmit={preventDefault}>
         <label class={style.optionTextFirst}>
           Method:
           <Select

src/codecs/webp/options.tsx

@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldCheckedAsNumber, inputFieldValueAsNumber } from '../../lib/util';
+import { inputFieldCheckedAsNumber, inputFieldValueAsNumber, preventDefault } from '../../lib/util';
 import { EncodeOptions, WebPImageHint } from './encoder-meta';
 import * as style from '../../components/Options/style.scss';
 import Checkbox from '../../components/checkbox';
@@ -319,7 +319,7 @@ export default class WebPEncoderOptions extends Component<Props, State> {
     // I'm rendering both lossy and lossless forms, as it becomes much easier when
     // gathering the data.
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <label class={style.optionInputFirst}>
           <Checkbox
             name="lossless"

src/components/App/index.tsx

@@ -12,6 +12,15 @@ import '../custom-els/LoadingSpinner';
 // This is imported for TypeScript only. It isn't used.
 import Compress from '../compress';
 
+const compressPromise = import(
+  /* webpackChunkName: "main-app" */
+  '../compress',
+);
+const offlinerPromise = import(
+  /* webpackChunkName: "offliner" */
+  '../../lib/offliner',
+);
+
 export interface SourceImage {
   file: File | Fileish;
   data: ImageData;
@@ -36,12 +45,14 @@ export default class App extends Component<Props, State> {
   constructor() {
     super();
 
-    import('../compress').then((module) => {
+    compressPromise.then((module) => {
       this.setState({ Compress: module.default });
     }).catch(() => {
       this.showSnack('Failed to load app');
     });
 
+    offlinerPromise.then(({ offliner }) => offliner(this.showSnack));
+
     // In development, persist application state across hot reloads:
     if (process.env.NODE_ENV === 'development') {
       this.setState(window.STATE);
@@ -71,6 +82,11 @@ export default class App extends Component<Props, State> {
     return this.snackbar.showSnackbar(message, options);
   }
 
+  @bind
+  private onBack() {
+    this.setState({ file: undefined });
+  }
+
   render({}: Props, { file, Compress }: State) {
     return (
       <div id="app" class={style.app}>
@@ -78,7 +94,7 @@ export default class App extends Component<Props, State> {
           {(!file)
             ? <Intro onFile={this.onIntroPickFile} showSnack={this.showSnack} />
             : (Compress)
-              ? <Compress file={file} showSnack={this.showSnack} />
+              ? <Compress file={file} showSnack={this.showSnack} onBack={this.onBack} />
               : <loading-spinner class={style.appLoader}/>
           }
           <snack-bar ref={linkRef(this, 'snackbar')} />

src/components/Output/custom-els/PinchZoom/index.ts

@@ -242,7 +242,7 @@ export default class PinchZoom extends HTMLElement {
   /**
    * Update transform values without checking bounds. This is only called in setTransform.
    */
-  _updateTransform(scale: number, x: number, y: number, allowChangeEvent: boolean) {
+  private _updateTransform(scale: number, x: number, y: number, allowChangeEvent: boolean) {
     // Avoid scaling to zero
     if (scale < MIN_SCALE) return;
 

src/components/Output/custom-els/TwoUp/index.ts

@@ -70,12 +70,13 @@ export default class TwoUp extends HTMLElement {
   connectedCallback() {
     this._childrenChange();
 
+    this._handle.innerHTML = `<div class="${styles.scrubber}">${
+      `<svg viewBox="0 0 27 20" fill="currentColor">${
+        '<path d="M17 19.2l9.5-9.6L16.9 0zM9.6 0L0 9.6l9.6 9.6z"/>'
+      }</svg>`
+    }</div>`;
+
     if (!this._everConnected) {
-      this._handle.innerHTML = `<div class="${styles.scrubber}">${
-        `<svg viewBox="0 0 27 20" fill="currentColor">${
-          '<path d="M17 19.2l9.5-9.6L16.9 0zM9.6 0L0 9.6l9.6 9.6z"/>'
-        }</svg>`
-      }</div>`;
       this._resetPosition();
       this._everConnected = true;
     }

src/components/Output/index.tsx

@@ -5,7 +5,7 @@ import './custom-els/TwoUp';
 import * as style from './style.scss';
 import { bind, linkRef } from '../../lib/initial-util';
 import { shallowEqual, drawDataToCanvas } from '../../lib/util';
-import { ToggleIcon, AddIcon, RemoveIcon } from '../../lib/icons';
+import { ToggleIcon, AddIcon, RemoveIcon, BackIcon } from '../../lib/icons';
 import { twoUpHandle } from './custom-els/TwoUp/styles.css';
 
 interface Props {
@@ -15,6 +15,7 @@ interface Props {
   rightCompressed?: ImageData;
   leftImgContain: boolean;
   rightImgContain: boolean;
+  onBack: () => void;
 }
 
 interface State {
@@ -47,6 +48,15 @@ export default class Output extends Component<Props, State> {
     const leftDraw = this.leftDrawable();
     const rightDraw = this.rightDrawable();
 
+    // Reset the pinch zoom, which may have an position set from the previous view, after pressing
+    // the back button.
+    this.pinchZoomLeft!.setTransform({
+      allowChangeEvent: true,
+      x: 0,
+      y: 0,
+      scale: 1,
+    });
+
     if (this.canvasLeft && leftDraw) {
       drawDataToCanvas(this.canvasLeft, leftDraw);
     }
@@ -191,7 +201,7 @@ export default class Output extends Component<Props, State> {
   }
 
   render(
-    { mobileView, leftImgContain, rightImgContain, originalImage }: Props,
+    { mobileView, leftImgContain, rightImgContain, originalImage, onBack }: Props,
     { scale, editingScale, altBackground }: State,
   ) {
     const leftDraw = this.leftDrawable();
@@ -243,6 +253,12 @@ export default class Output extends Component<Props, State> {
           </pinch-zoom>
         </two-up>
 
+        <div class={style.back}>
+          <button class={style.button} onClick={onBack}>
+            <BackIcon />
+          </button>
+        </div>
+
         <div class={style.controls}>
           <div class={style.zoomControls}>
             <button class={style.button} onClick={this.zoomOut}>

src/components/Output/style.scss

@@ -38,7 +38,7 @@
   top: 0;
   left: 0;
   right: 0;
-  padding: 9px;
+  padding: 9px 84px;
   overflow: hidden;
   flex-wrap: wrap;
   contain: content;
@@ -50,6 +50,7 @@
   }
 
   @media (min-width: 860px) {
+    padding: 9px;
     top: auto;
     left: 320px;
     right: 320px;
@@ -78,14 +79,19 @@
   display: flex;
   align-items: center;
   box-sizing: border-box;
-  height: 48px;
-  padding: 0 16px;
   margin: 4px;
   background-color: #fff;
   border: 1px solid rgba(0,0,0,0.2);
   border-radius: 5px;
   line-height: 1;
   white-space: nowrap;
+  height: 36px;
+  padding: 0 8px;
+
+  @media (min-width: 600px) {
+    height: 48px;
+    padding: 0 16px;
+  }
 
   &:focus {
     box-shadow: 0 0 0 2px var(--button-fg);
@@ -134,3 +140,10 @@
   // https://bugs.chromium.org/p/chromium/issues/detail?id=870222#c10
   will-change: auto;
 }
+
+.back {
+  position: absolute;
+  top: 0;
+  left: 0;
+  padding: 9px;
+}

src/components/compress/custom-els/MultiPanel/index.ts

@@ -103,7 +103,7 @@ export default class MultiPanel extends HTMLElement {
 
   // KeyDown event handler
   private _onKeyDown(event: KeyboardEvent) {
-    const selectedEl = document.activeElement;
+    const selectedEl = document.activeElement!;
     const heading = getClosestHeading(selectedEl);
 
     // if keydown event is not on heading element, ignore
@@ -252,8 +252,8 @@ export default class MultiPanel extends HTMLElement {
       return this.firstElementChild as HTMLElement;
     }
     // previous Element of active Element is previous Content,
-    // previous Element of previous Content  is previousHeading
+    // previous Element of previous Content is previousHeading
-    const previousContent = document.activeElement.previousElementSibling;
+    const previousContent = document.activeElement!.previousElementSibling;
     if (previousContent) {
       return previousContent.previousElementSibling as HTMLElement;
     }
@@ -263,7 +263,7 @@ export default class MultiPanel extends HTMLElement {
   private _nextHeading() {
     // activeElement would be the currently selected heading
     // 2 elemements after that would be the next heading.
-    const nextContent = document.activeElement.nextElementSibling;
+    const nextContent = document.activeElement!.nextElementSibling;
     if (nextContent) {
       return nextContent.nextElementSibling as HTMLElement;
     }

src/components/compress/index.tsx

@@ -60,6 +60,7 @@ interface EncodedImage {
 interface Props {
   file: File | Fileish;
   showSnack: SnackBarElement['showSnackbar'];
+  onBack: () => void;
 }
 
 interface State {
@@ -195,6 +196,8 @@ export default class Compress extends Component<Props, State> {
     super(props);
     this.widthQuery.addListener(this.onMobileWidthChange);
     this.updateFile(props.file);
+
+    import('../../lib/offliner').then(({ mainAppLoaded }) => mainAppLoaded());
   }
 
   @bind
@@ -413,7 +416,7 @@ export default class Compress extends Component<Props, State> {
     this.setState({ images });
   }
 
-  render({ }: Props, { loading, images, source, mobileView }: State) {
+  render({ onBack }: Props, { loading, images, source, mobileView }: State) {
     const [leftImage, rightImage] = images;
     const [leftImageData, rightImageData] = images.map(i => i.data);
 
@@ -458,6 +461,7 @@ export default class Compress extends Component<Props, State> {
           rightCompressed={rightImageData}
           leftImgContain={leftImage.preprocessorState.resize.fitMethod === 'cover'}
           rightImgContain={rightImage.preprocessorState.resize.fitMethod === 'cover'}
+          onBack={onBack}
         />
         {mobileView
           ? (

src/components/compress/style.scss

@@ -22,7 +22,7 @@
   max-width: 400px;
   margin: 0 auto;
   width: calc(100% - 60px);
-  max-height: calc(100% - 143px);
+  max-height: calc(100% - 104px);
   overflow: hidden;
 
   @media (min-width: 600px) {

src/components/intro/index.tsx

@@ -4,13 +4,13 @@ import { bind, linkRef, Fileish } from '../../lib/initial-util';
 import '../custom-els/LoadingSpinner';
 
 import logo from './imgs/logo.svg';
-import largePhoto from './imgs/demos/large-photo.jpg';
+import largePhoto from './imgs/demos/demo-large-photo.jpg';
-import artwork from './imgs/demos/artwork.jpg';
+import artwork from './imgs/demos/demo-artwork.jpg';
-import deviceScreen from './imgs/demos/device-screen.png';
+import deviceScreen from './imgs/demos/demo-device-screen.png';
-import largePhotoIcon from './imgs/demos/large-photo-icon.jpg';
+import largePhotoIcon from './imgs/demos/icon-demo-large-photo.jpg';
-import artworkIcon from './imgs/demos/artwork-icon.jpg';
+import artworkIcon from './imgs/demos/icon-demo-artwork.jpg';
-import deviceScreenIcon from './imgs/demos/device-screen-icon.jpg';
+import deviceScreenIcon from './imgs/demos/icon-demo-device-screen.jpg';
-import logoIcon from './imgs/demos/logo-icon.png';
+import logoIcon from './imgs/demos/icon-demo-logo.png';
 import * as style from './style.scss';
 import SnackBarElement from '../../lib/SnackBar';
 
@@ -90,7 +90,7 @@ export default class Intro extends Component<Props, State> {
         <div>
           <div class={style.logoSizer}>
             <div class={style.logoContainer}>
-              <img src={logo} class={style.logo} alt="Squoosh" />
+              <img src={logo} class={style.logo} alt="Squoosh" decoding="async" />
             </div>
           </div>
           <p class={style.openImageGuide}>
@@ -111,7 +111,7 @@ export default class Intro extends Component<Props, State> {
                   <div class={style.demo}>
                     <div class={style.demoImgContainer}>
                       <div class={style.demoImgAspect}>
-                        <img class={style.demoIcon} src={demo.iconUrl} alt=""/>
+                        <img class={style.demoIcon} src={demo.iconUrl} alt="" decoding="async" />
                         {fetchingDemoIndex === i &&
                           <div class={style.demoLoading}>
                             <loading-spinner class={style.demoLoadingSpinner}/>
@@ -129,6 +129,11 @@ export default class Intro extends Component<Props, State> {
         <ul class={style.relatedLinks}>
           <li><a href="https://github.com/GoogleChromeLabs/squoosh/">View the code</a></li>
           <li><a href="https://github.com/GoogleChromeLabs/squoosh/issues">Report a bug</a></li>
+          <li>
+            <a href="https://github.com/GoogleChromeLabs/squoosh/blob/master/README.md#privacy">
+              Privacy
+            </a>
+          </li>
         </ul>
       </div>
     );

src/components/intro/style.scss

@@ -2,6 +2,7 @@
   font-family: 'intro-text';
   font-style: normal;
   font-weight: 300;
+  font-display: block;
   // This only contains the chars for "Drag & drop or"
   src: url('data:font/woff2;base64,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') format('woff2');
 }
@@ -10,6 +11,7 @@
   font-family: 'intro-text';
   font-style: normal;
   font-weight: 500;
+  font-display: block;
   // Only contains the chars for "select an image"
   src: url('data:font/woff2;base64,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') format('woff2');
 }
@@ -40,16 +42,17 @@
 
 .logo-sizer {
   width: 90%;
-  max-width: 480px;
+  max-width: 52vh;
   margin: 0 auto;
 }
 
 .logo {
   composes: abs-fill from '../../lib/util.scss';
+  pointer-events: none;
 }
 
 .open-image-guide {
-  font: 300 11vw intro-text;
+  font: 300 11vw intro-text, sans-serif;
   margin-bottom: 0;
 
   @media (min-width: 460px) {
@@ -142,6 +145,7 @@
 
 .demo-icon {
   composes: abs-fill from '../../lib/util.scss';
+  pointer-events: none;
 }
 
 .demo-description {

src/components/range/index.tsx

@@ -13,6 +13,8 @@ export default class Range extends Component<Props, State> {
   @bind
   private onTextInput(event: Event) {
     const input = event.target as HTMLInputElement;
+    const value = input.value.trim();
+    if (!value) return;
     this.rangeWc!.value = input.value;
     const { onInput } = this.props;
     if (onInput) onInput(event);

src/components/results/index.tsx

@@ -58,6 +58,21 @@ export default class Results extends Component<Props, State> {
     this.props.onCopyToOtherClick();
   }
 
+  @bind
+  onDownload() {
+    // GA can’t do floats. So we round to ints. We're deliberately rounding to nearest kilobyte to
+    // avoid cases where exact image sizes leak something interesting about the user.
+    const before = Math.round(this.props.source!.file.size / 1024);
+    const after = Math.round(this.props.imageFile!.size / 1024);
+    const change = Math.round(after / before * 1000);
+
+    ga('send', 'event', 'compression', 'download', {
+      metric1: before,
+      metric2: after,
+      metric3: change,
+    });
+  }
+
   render(
     { source, imageFile, downloadUrl, children, copyDirection, buttonPosition }: Props,
     { showLoadingState }: State,
@@ -93,6 +108,7 @@ export default class Results extends Component<Props, State> {
               href={downloadUrl}
               download={imageFile.name}
               title="Download"
+              onClick={this.onDownload}
             >
               <DownloadIcon class={style.downloadIcon} />
             </a>

src/index.html

@@ -4,13 +4,13 @@
     <meta charset="utf-8">
     <title>Squoosh</title>
     <meta name="description" content="Compress and compare images with different codecs, right in your browser">
-    <meta name="viewport" content="width=device-width,initial-scale=1">
+    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
     <meta name="mobile-web-app-capable" content="yes">
     <meta name="apple-mobile-web-app-capable" content="yes">
-    <meta name="theme-color" content="#673ab8">
+    <link rel="shortcut icon" href="/assets/favicon.ico">
+    <meta name="theme-color" content="#f78f21">
     <link rel="manifest" href="/manifest.json">
   </head>
   <body>
-    <div id="app"></div>
   </body>
 </html>

src/index.ts

@@ -1,9 +1,25 @@
 declare module '@webcomponents/custom-elements';
 
-(async function () {
+function init() {
-  if (!('customElements' in self)) {
-    await import('@webcomponents/custom-elements');
-  }
-
   require('./init-app.tsx');
-})();
+}
+
+if (!('customElements' in self)) {
+  import(
+    /* webpackChunkName: "wc-polyfill" */
+    '@webcomponents/custom-elements',
+  ).then(init);
+} else {
+  init();
+}
+
+if (typeof PRERENDER === 'undefined') {
+  window.ga = window.ga || ((...args) => (ga.q = ga.q || []).push(args));
+  ga('create', 'UA-128752250-1', 'auto');
+  ga('set', 'transport', 'beacon');
+  ga('send', 'pageview');
+    // Load the GA script
+  const s = document.createElement('script');
+  s.src = 'https://www.google-analytics.com/analytics.js';
+  document.head!.appendChild(s);
+}

src/init-app.tsx

@@ -4,13 +4,13 @@ import './style';
 import App from './components/App';
 
 // Find the outermost Element in our server-rendered HTML structure.
-let root = document.querySelector('#app') || undefined;
+let root = document.getElementById('app_root') as Element;
 
 // "attach" the client-side rendering to it, updating the DOM in-place instead of replacing:
 root = render(<App />, document.body, root);
+root.setAttribute('id', 'app_root');
 
-// In production, this entire condition is removed.
+if (process.env.NODE_ENV !== 'production') {
-if (process.env.NODE_ENV === 'development') {
   // Enable support for React DevTools and some helpful console warnings:
   require('preact/debug');
 

src/lib/SnackBar/index.ts

@@ -8,12 +8,9 @@ export interface SnackOptions {
 function createSnack(message: string, options: SnackOptions): [Element, Promise<string>] {
   const {
     timeout = 0,
-    actions = [],
+    actions = ['dismiss'],
   } = options;
 
-  // Provide a default 'dismiss' action
-  if (!timeout && actions.length === 0) actions.push('dismiss');
-
   const el = document.createElement('div');
   el.className = style.snackbar;
   el.setAttribute('aria-live', 'assertive');

src/lib/icons.tsx

@@ -48,6 +48,12 @@ export const ExpandIcon = (props: JSX.HTMLAttributes) => (
   </Icon>
 );
 
+export const BackIcon = (props: JSX.HTMLAttributes) => (
+  <Icon {...props}>
+    <path d="M20 11H7.8l5.6-5.6L12 4l-8 8 8 8 1.4-1.4L7.8 13H20v-2z"/>
+  </Icon>
+);
+
 const copyAcrossRotations = {
   up: 90, right: 180, down: -90, left: 0,
 };

src/lib/offliner.ts

@@ -0,0 +1,98 @@
+import { get, set } from 'idb-keyval';
+
+// Just for TypeScript
+import SnackBarElement from './SnackBar';
+
+/** Tell the service worker to skip waiting */
+async function skipWaiting() {
+  const reg = await navigator.serviceWorker.getRegistration();
+  if (!reg || !reg.waiting) return;
+  reg.waiting.postMessage('skip-waiting');
+}
+
+/** Find the service worker that's 'active' or closest to 'active' */
+async function getMostActiveServiceWorker() {
+  const reg = await navigator.serviceWorker.getRegistration();
+  if (!reg) return null;
+  return reg.active || reg.waiting || reg.installing;
+}
+
+/** Wait for an installing worker */
+async function installingWorker(reg: ServiceWorkerRegistration): Promise<ServiceWorker> {
+  if (reg.installing) return reg.installing;
+  return new Promise<ServiceWorker>((resolve) => {
+    reg.addEventListener(
+      'updatefound',
+      () => resolve(reg.installing!),
+      { once: true },
+    );
+  });
+}
+
+/** Wait a service worker to become waiting */
+async function updateReady(reg: ServiceWorkerRegistration): Promise<void> {
+  if (reg.waiting) return;
+  const installing = await installingWorker(reg);
+  return new Promise<void>((resolve) => {
+    installing.addEventListener('statechange', () => {
+      if (installing.state === 'installed') resolve();
+    });
+  });
+}
+
+/** Set up the service worker and monitor changes */
+export async function offliner(showSnack: SnackBarElement['showSnackbar']) {
+  // This needs to be a typeof because Webpack.
+  if (typeof PRERENDER === 'boolean') return;
+
+  if (process.env.NODE_ENV === 'production') {
+    navigator.serviceWorker.register('../sw');
+  }
+
+  const hasController = !!navigator.serviceWorker.controller;
+
+  // Look for changes in the controller
+  navigator.serviceWorker.addEventListener('controllerchange', async () => {
+    // Is it the first install?
+    if (!hasController) {
+      showSnack('Ready to work offline', { timeout: 5000 });
+      return;
+    }
+
+    // Otherwise reload (the user will have agreed to this).
+    location.reload();
+  });
+
+  // If we don't have a controller, we don't need to check for updates – we've just loaded from the
+  // network.
+  if (!hasController) return;
+
+  const reg = await navigator.serviceWorker.getRegistration();
+  // Service worker not registered yet.
+  if (!reg) return;
+  // Look for updates
+  await updateReady(reg);
+
+  // Ask the user if they want to update.
+  const result = await showSnack('Update available', {
+    actions: ['reload', 'dismiss'],
+  });
+
+  // Tell the waiting worker to activate, this will change the controller and cause a reload (see
+  // 'controllerchange')
+  if (result === 'reload') skipWaiting();
+}
+
+/**
+ * Tell the service worker the main app has loaded. If it's the first time the service worker has
+ * heard about this, cache the heavier assets like codecs.
+ */
+export async function mainAppLoaded() {
+  // If the user has already interacted, no need to tell the service worker anything.
+  const userInteracted = await get<boolean | undefined>('user-interacted');
+  if (userInteracted) return;
+  set('user-interacted', true);
+  const serviceWorker = await getMostActiveServiceWorker();
+  if (!serviceWorker) return; // Service worker not installing yet.
+  serviceWorker.postMessage('cache-all');
+}

src/lib/util.ts

@@ -297,3 +297,10 @@ export async function transitionHeight(el: HTMLElement, opts: TransitionOptions)
     el.addEventListener('transitioncancel', listener);
   });
 }
+
+/**
+ * Simple event listener that prevents the default.
+ */
+export function preventDefault(event: Event) {
+  event.preventDefault();
+}

src/manifest.json

@@ -3,14 +3,14 @@
   "short_name": "Squoosh",
   "start_url": "/",
   "display": "standalone",
-  "orientation": "portrait",
+  "orientation": "any",
   "background_color": "#fff",
-  "theme_color": "#673ab8",
+  "theme_color": "#f78f21",
   "icons": [
     {
-      "src": "/assets/icon.png",
+      "src": "/assets/icon-large.png",
       "type": "image/png",
-      "sizes": "512x512"
+      "sizes": "1024x1024"
     }
   ]
 }

src/missing-types.d.ts

@@ -27,3 +27,15 @@ declare module '*.wasm' {
   const content: string;
   export default content;
 }
+
+declare module 'url-loader!*' {
+  const value: string;
+  export default value;
+}
+
+declare var VERSION: string;
+
+declare var ga: {
+  (...args: any[]): void;
+  q: any[];
+};

src/sw/index.ts

@@ -0,0 +1,69 @@
+import {
+  cacheOrNetworkAndCache, cleanupCache, cacheOrNetwork, cacheBasics, cacheAdditionalProcessors,
+} from './util';
+import { get } from 'idb-keyval';
+
+// Give TypeScript the correct global.
+declare var self: ServiceWorkerGlobalScope;
+// This is populated by webpack.
+declare var BUILD_ASSETS: string[];
+
+const versionedCache = 'static-' + VERSION;
+const dynamicCache = 'dynamic';
+const expectedCaches = [versionedCache, dynamicCache];
+
+self.addEventListener('install', (event) => {
+  event.waitUntil(async function () {
+    const promises = [];
+    promises.push(cacheBasics(versionedCache, BUILD_ASSETS));
+
+    // If the user has already interacted with the app, update the codecs too.
+    if (await get('user-interacted')) {
+      promises.push(cacheAdditionalProcessors(versionedCache, BUILD_ASSETS));
+    }
+
+    await Promise.all(promises);
+  }());
+});
+
+self.addEventListener('activate', (event) => {
+  self.clients.claim();
+
+  event.waitUntil(async function () {
+    // Remove old caches.
+    const promises = (await caches.keys()).map((cacheName) => {
+      if (!expectedCaches.includes(cacheName)) return caches.delete(cacheName);
+    });
+
+    await Promise.all<any>(promises);
+  }());
+});
+
+self.addEventListener('fetch', (event) => {
+  // We only care about GET.
+  if (event.request.method !== 'GET') return;
+
+  const url = new URL(event.request.url);
+
+  // Don't care about other-origin URLs
+  if (url.origin !== location.origin) return;
+
+  if (url.pathname.startsWith('/demo-') || url.pathname.startsWith('/wc-polyfill')) {
+    cacheOrNetworkAndCache(event, dynamicCache);
+    cleanupCache(event, dynamicCache, BUILD_ASSETS);
+    return;
+  }
+
+  cacheOrNetwork(event);
+});
+
+self.addEventListener('message', (event) => {
+  switch (event.data) {
+    case 'cache-all':
+      event.waitUntil(cacheAdditionalProcessors(versionedCache, BUILD_ASSETS));
+      break;
+    case 'skip-waiting':
+      self.skipWaiting();
+      break;
+  }
+});

src/sw/missing-types.d.ts

@@ -0,0 +1 @@
+import '../missing-types';

src/sw/tsconfig.json

@@ -0,0 +1,18 @@
+{
+  "compileOnSave": false,
+  "compilerOptions": {
+    "strict": true,
+    "target": "esnext",
+    "module": "esnext",
+    "lib": [
+      "webworker",
+      "esnext"
+    ],
+    "moduleResolution": "node",
+    "experimentalDecorators": true,
+    "noUnusedLocals": true,
+    "sourceMap": true,
+    "allowJs": false,
+    "baseUrl": "."
+  }
+}

src/sw/util.ts

@@ -0,0 +1,106 @@
+import webpDataUrl from 'url-loader!../codecs/tiny.webp';
+
+export function cacheOrNetwork(event: FetchEvent): void {
+  event.respondWith(async function () {
+    const cachedResponse = await caches.match(event.request);
+    return cachedResponse || fetch(event.request);
+  }());
+}
+
+export function cacheOrNetworkAndCache(event: FetchEvent, cacheName: string): void {
+  event.respondWith(async function () {
+    const { request } = event;
+    // Return from cache if possible.
+    const cachedResponse = await caches.match(request);
+    if (cachedResponse) return cachedResponse;
+
+    // Else go to the network.
+    const response = await fetch(request);
+    const responseToCache = response.clone();
+
+    event.waitUntil(async function () {
+      // Cache what we fetched.
+      const cache = await caches.open(cacheName);
+      await cache.put(request, responseToCache);
+    }());
+
+    // Return the network response.
+    return response;
+  }());
+}
+
+export function cleanupCache(event: FetchEvent, cacheName: string, keepAssets: string[]) {
+  event.waitUntil(async function () {
+    const cache = await caches.open(cacheName);
+
+    // Clean old entries from the dynamic cache.
+    const requests = await cache.keys();
+    const promises = requests.map((cachedRequest) => {
+      // Get pathname without leading /
+      const assetPath = new URL(cachedRequest.url).pathname.slice(1);
+      // If it isn't one of our keepAssets, we don't need it anymore.
+      if (!keepAssets.includes(assetPath)) return cache.delete(cachedRequest);
+    });
+
+    await Promise.all<any>(promises);
+  }());
+}
+
+function getAssetsWithPrefix(assets: string[], prefixes: string[]) {
+  return assets.filter(
+    asset => prefixes.some(prefix => asset.startsWith(prefix)),
+  );
+}
+
+export async function cacheBasics(cacheName: string, buildAssets: string[]) {
+  const toCache = ['/', '/assets/favicon.ico'];
+
+  const prefixesToCache = [
+    // Main app JS & CSS:
+    'main-app.',
+    // Service worker handler:
+    'offliner.',
+    // Little icons for the demo images on the homescreen:
+    'icon-demo-',
+    // Site logo:
+    'logo.',
+  ];
+
+  const prefixMatches = getAssetsWithPrefix(buildAssets, prefixesToCache);
+
+  toCache.push(...prefixMatches);
+
+  const cache = await caches.open(cacheName);
+  await cache.addAll(toCache);
+}
+
+export async function cacheAdditionalProcessors(cacheName: string, buildAssets: string[]) {
+  let toCache = [];
+
+  const prefixesToCache = [
+    // Worker which handles image processing:
+    'processor-worker.',
+    // processor-worker imports:
+    'process-',
+  ];
+
+  const prefixMatches = getAssetsWithPrefix(buildAssets, prefixesToCache);
+  const wasm = buildAssets.filter(asset => asset.endsWith('.wasm'));
+
+  toCache.push(...prefixMatches, ...wasm);
+
+  const supportsWebP = await (async () => {
+    if (!self.createImageBitmap) return false;
+    const response = await fetch(webpDataUrl);
+    const blob = await response.blob();
+    return createImageBitmap(blob).then(() => true, () => false);
+  })();
+
+  // No point caching the WebP decoder if it's supported natively:
+  if (supportsWebP) {
+    toCache = toCache.filter(asset => !/webp[\-_]dec/.test(asset));
+  }
+
+  const cache = await caches.open(cacheName);
+  await cache.addAll(toCache);
+}

tsconfig.json

@@ -12,5 +12,6 @@
     "jsxFactory": "h",
     "allowJs": false,
     "baseUrl": "."
-  }
+  },
+  "exclude": ["src/sw/**/*"]
 }

webpack.config.js

@@ -2,22 +2,26 @@ const fs = require('fs');
 const path = require('path');
 const webpack = require('webpack');
 const CleanPlugin = require('clean-webpack-plugin');
-const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
+const TerserPlugin = require('terser-webpack-plugin');
 const ProgressBarPlugin = require('progress-bar-webpack-plugin');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
 const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');
 const HtmlPlugin = require('html-webpack-plugin');
 const ScriptExtHtmlPlugin = require('script-ext-html-webpack-plugin');
-const ReplacePlugin = require('webpack-plugin-replace');
 const CopyPlugin = require('copy-webpack-plugin');
 const WatchTimestampsPlugin = require('./config/watch-timestamps-plugin');
 const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
 const WorkerPlugin = require('worker-plugin');
+const AutoSWPlugin = require('./config/auto-sw-plugin');
+const CrittersPlugin = require('critters-webpack-plugin');
+const AssetTemplatePlugin = require('./config/asset-template-plugin');
 
 function readJson (filename) {
   return JSON.parse(fs.readFileSync(filename));
 }
 
+const VERSION = readJson('./package.json').version;
+
 module.exports = function (_, env) {
   const isProd = env.mode === 'production';
   const nodeModules = path.join(__dirname, 'node_modules');
@@ -30,12 +34,14 @@ module.exports = function (_, env) {
 
   return {
     mode: isProd ? 'production' : 'development',
-    entry: './src/index',
+    entry: {
+      'first-interaction': './src/index'
+    },
     devtool: isProd ? 'source-map' : 'inline-source-map',
     stats: 'minimal',
     output: {
       filename: isProd ? '[name].[chunkhash:5].js' : '[name].js',
-      chunkFilename: '[name].chunk.[chunkhash:5].js',
+      chunkFilename: '[name].[chunkhash:5].js',
       path: path.join(__dirname, 'build'),
       publicPath: '/',
       globalObject: 'self'
@@ -138,12 +144,6 @@ module.exports = function (_, env) {
           exclude: nodeModules,
           loader: 'ts-loader'
         },
-        {
-          test: /\.jsx?$/,
-          loader: 'babel-loader',
-          // Don't respect any Babel RC files found on the filesystem:
-          options: Object.assign(readJson('.babelrc'), { babelrc: false })
-        },
         {
           // All the codec files define a global with the same name as their file name. `exports-loader` attaches those to `module.exports`.
           test: /\/codecs\/.*\.js$/,
@@ -154,11 +154,17 @@ module.exports = function (_, env) {
           // This is needed to make webpack NOT process wasm files.
           // See https://github.com/webpack/webpack/issues/6725
           type: 'javascript/auto',
-          loader: 'file-loader'
+          loader: 'file-loader',
+          options: {
+            name: '[name].[hash:5].[ext]',
+          },
         },
         {
           test: /\.(png|svg|jpg|gif)$/,
-          loader: 'file-loader'
+          loader: 'file-loader',
+          options: {
+            name: '[name].[hash:5].[ext]',
+          },
         }
       ]
     },
@@ -195,7 +201,7 @@ module.exports = function (_, env) {
       // See also: https://twitter.com/wsokra/status/970253245733113856
       isProd && new MiniCssExtractPlugin({
         filename: '[name].[contenthash:5].css',
-        chunkFilename: '[name].chunk.[contenthash:5].css'
+        chunkFilename: '[name].[contenthash:5].css'
       }),
 
       new OptimizeCssAssetsPlugin({
@@ -220,7 +226,7 @@ module.exports = function (_, env) {
       // For now we're not doing SSR.
       new HtmlPlugin({
         filename: path.join(__dirname, 'build/index.html'),
-        template: 'src/index.html',
+        template: isProd ? '!!prerender-loader?string!src/index.html' : 'src/index.html',
         minify: isProd && {
           collapseWhitespace: true,
           removeScriptTypeAttributes: true,
@@ -229,32 +235,29 @@ module.exports = function (_, env) {
           removeComments: true
         },
         manifest: readJson('./src/manifest.json'),
-        inject: true,
+        inject: 'body',
         compile: true
       }),
 
+      new AutoSWPlugin({ version: VERSION }),
+
+      isProd && new AssetTemplatePlugin({
+        template: path.join(__dirname, '_headers.ejs'),
+        filename: '_headers',
+      }),
+
       new ScriptExtHtmlPlugin({
-        defaultAttribute: 'async'
+        inline: ['first']
       }),
 
       // Inline constants during build, so they can be folded by UglifyJS.
       new webpack.DefinePlugin({
+        VERSION: JSON.stringify(VERSION),
         // We set node.process=false later in this config.
         // Here we make sure if (process && process.foo) still works:
         process: '{}'
       }),
 
-      // Babel embeds helpful error messages into transpiled classes that we don't need in production.
-      // Here we replace the constructor and message with a static throw, leaving the message to be DCE'd.
-      // This is useful since it shows the message in SourceMapped code when debugging.
-      isProd && new ReplacePlugin({
-        include: /babel-helper$/,
-        patterns: [{
-          regex: /throw\s+(?:new\s+)?((?:Type|Reference)?Error)\s*\(/g,
-          value: (s, type) => `throw 'babel error'; (`
-        }]
-      }),
-
       // Copying files via Webpack allows them to be served dynamically by `webpack serve`
       new CopyPlugin([
         { from: 'src/manifest.json', to: 'manifest.json' },
@@ -266,17 +269,31 @@ module.exports = function (_, env) {
         analyzerMode: 'static',
         defaultSizes: 'gzip',
         openAnalyzer: false
+      }),
+
+      // Inline Critical CSS (for the intro screen, essentially)
+      isProd && new CrittersPlugin({
+        // use <link rel="stylesheet" media="not x" onload="this.media='all'"> hack to load async css:
+        preload: 'media',
+        // inline all styles from any stylesheet below this size:
+        inlineThreshold: 2000,
+        // don't bother lazy-loading non-critical stylesheets below this size, just inline the non-critical styles too:
+        minimumExternalSize: 4000,
+        // don't emit <noscript> external stylesheet links since the app fundamentally requires JS anyway:
+        noscriptFallback: false,
+        // inline the tiny data URL fonts we have for the intro screen:
+        inlineFonts: true,
+        // (and don't lazy load them):
+        preloadFonts: false
       })
     ].filter(Boolean), // Filter out any falsey plugin array entries.
 
     optimization: {
       minimizer: [
-        new UglifyJsPlugin({
+        new TerserPlugin({
           sourceMap: isProd,
-          extractComments: {
+          extractComments: 'build/licenses.txt',
-            file: 'build/licenses.txt'
+          terserOptions: {
-          },
-          uglifyOptions: {
             compress: {
               inline: 1
             },