[example] Add preact-next example (#15401)

Author: oliviertassinari

.eslintignore

@@ -3,8 +3,8 @@
 /coverage
 /docs/export
 /examples/create-react-app*/src/serviceWorker.js
-/examples/create-react-app-with-flow/flow
-/examples/create-react-app-with-flow/flow-typed
+/examples/preact-next/config
+/examples/preact-next/scripts
 /examples/gatsby/public
 /packages/babel-plugin-unwrap-createStyles/test/__fixtures__/
 /packages/material-ui-codemod/lib

examples/preact-next/.gitignore

@@ -0,0 +1,27 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# production
+/build
+
+# IDEs and editors
+/.idea
+/.vscode
+
+# misc
+.DS_Store
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

examples/preact-next/README.md

@@ -0,0 +1,32 @@
+# Preact v4-alpha example
+
+## How to use
+
+Download the example [or clone the repo](https://github.com/mui-org/material-ui):
+
+```sh
+curl https://codeload.github.com/mui-org/material-ui/tar.gz/next | tar -xz --strip=2  material-ui-next/examples/preact-next
+cd preact-next
+```
+
+Install it and run:
+
+```sh
+npm install
+npm run start
+```
+
+## The idea behind the example
+
+[Preact](https://github.com/developit/preact) is a fast 3kB alternative to React with the same modern API.
+
+This example uses an ejected version of CRA.
+It's ejected to change the webpack configuration:
+
+```js
+alias: {
+  // Use Preact instead of React.
+  'react': 'preact/compat',
+  'react-dom': 'preact/compat',
+}
+```

examples/preact-next/config/env.js

@@ -0,0 +1,91 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const paths = require('./paths');
+
+// Make sure that including paths.js after env.js will read .env variables.
+delete require.cache[require.resolve('./paths')];
+
+const NODE_ENV = process.env.NODE_ENV;
+if (!NODE_ENV) {
+  throw new Error('The NODE_ENV environment variable is required but was not specified.');
+}
+
+// https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use
+var dotenvFiles = [
+  `${paths.dotenv}.${NODE_ENV}.local`,
+  `${paths.dotenv}.${NODE_ENV}`,
+  // Don't include `.env.local` for `test` environment
+  // since normally you expect tests to produce the same
+  // results for everyone
+  NODE_ENV !== 'test' && `${paths.dotenv}.local`,
+  paths.dotenv,
+].filter(Boolean);
+
+// Load environment variables from .env* files. Suppress warnings using silent
+// if this file is missing. dotenv will never modify any environment variables
+// that have already been set.  Variable expansion is supported in .env files.
+// https://github.com/motdotla/dotenv
+// https://github.com/motdotla/dotenv-expand
+dotenvFiles.forEach(dotenvFile => {
+  if (fs.existsSync(dotenvFile)) {
+    require('dotenv-expand')(
+      require('dotenv').config({
+        path: dotenvFile,
+      }),
+    );
+  }
+});
+
+// We support resolving modules according to `NODE_PATH`.
+// This lets you use absolute paths in imports inside large monorepos:
+// https://github.com/facebook/create-react-app/issues/253.
+// It works similar to `NODE_PATH` in Node itself:
+// https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders
+// Note that unlike in Node, only *relative* paths from `NODE_PATH` are honored.
+// Otherwise, we risk importing Node.js core modules into an app instead of Webpack shims.
+// https://github.com/facebook/create-react-app/issues/1023#issuecomment-265344421
+// We also resolve them to make sure all tools using them work consistently.
+const appDirectory = fs.realpathSync(process.cwd());
+process.env.NODE_PATH = (process.env.NODE_PATH || '')
+  .split(path.delimiter)
+  .filter(folder => folder && !path.isAbsolute(folder))
+  .map(folder => path.resolve(appDirectory, folder))
+  .join(path.delimiter);
+
+// Grab NODE_ENV and REACT_APP_* environment variables and prepare them to be
+// injected into the application via DefinePlugin in Webpack configuration.
+const REACT_APP = /^REACT_APP_/i;
+
+function getClientEnvironment(publicUrl) {
+  const raw = Object.keys(process.env)
+    .filter(key => REACT_APP.test(key))
+    .reduce(
+      (env, key) => {
+        env[key] = process.env[key];
+        return env;
+      },
+      {
+        // Useful for determining whether we’re running in production mode.
+        // Most importantly, it switches React into the correct mode.
+        NODE_ENV: process.env.NODE_ENV || 'development',
+        // Useful for resolving the correct path to static assets in `public`.
+        // For example, <img src={process.env.PUBLIC_URL + '/img/logo.png'} />.
+        // This should only be used as an escape hatch. Normally you would put
+        // images into the `src` and `import` them in code to get their paths.
+        PUBLIC_URL: publicUrl,
+      },
+    );
+  // Stringify all values so we can feed into Webpack DefinePlugin
+  const stringified = {
+    'process.env': Object.keys(raw).reduce((env, key) => {
+      env[key] = JSON.stringify(raw[key]);
+      return env;
+    }, {}),
+  };
+
+  return { raw, stringified };
+}
+
+module.exports = getClientEnvironment;

examples/preact-next/config/jest/cssTransform.js

@@ -0,0 +1,14 @@
+'use strict';
+
+// This is a custom Jest transformer turning style imports into empty objects.
+// http://facebook.github.io/jest/docs/en/webpack.html
+
+module.exports = {
+  process() {
+    return 'module.exports = {};';
+  },
+  getCacheKey() {
+    // The output is always the same.
+    return 'cssTransform';
+  },
+};

examples/preact-next/config/jest/fileTransform.js

@@ -0,0 +1,31 @@
+'use strict';
+
+const path = require('path');
+
+// This is a custom Jest transformer turning file imports into filenames.
+// http://facebook.github.io/jest/docs/en/webpack.html
+
+module.exports = {
+  process(src, filename) {
+    const assetFilename = JSON.stringify(path.basename(filename));
+
+    if (filename.match(/\.svg$/)) {
+      return `const React = require('react');
+      module.exports = {
+        __esModule: true,
+        default: ${assetFilename},
+        ReactComponent: React.forwardRef((props, ref) => ({
+          $$typeof: Symbol.for('react.element'),
+          type: 'svg',
+          ref: ref,
+          key: null,
+          props: Object.assign({}, props, {
+            children: ${assetFilename}
+          })
+        })),
+      };`;
+    }
+
+    return `module.exports = ${assetFilename};`;
+  },
+};

examples/preact-next/config/paths.js

@@ -0,0 +1,85 @@
+'use strict';
+
+const path = require('path');
+const fs = require('fs');
+const url = require('url');
+
+// Make sure any symlinks in the project folder are resolved:
+// https://github.com/facebook/create-react-app/issues/637
+const appDirectory = fs.realpathSync(process.cwd());
+const resolveApp = relativePath => path.resolve(appDirectory, relativePath);
+
+const envPublicUrl = process.env.PUBLIC_URL;
+
+function ensureSlash(inputPath, needsSlash) {
+  const hasSlash = inputPath.endsWith('/');
+  if (hasSlash && !needsSlash) {
+    return inputPath.substr(0, inputPath.length - 1);
+  } else if (!hasSlash && needsSlash) {
+    return `${inputPath}/`;
+  } else {
+    return inputPath;
+  }
+}
+
+const getPublicUrl = appPackageJson => envPublicUrl || require(appPackageJson).homepage;
+
+// We use `PUBLIC_URL` environment variable or "homepage" field to infer
+// "public path" at which the app is served.
+// Webpack needs to know it to put the right <script> hrefs into HTML even in
+// single-page apps that may serve index.html for nested URLs like /todos/42.
+// We can't use a relative path in HTML because we don't want to load something
+// like /todos/42/static/js/bundle.7289d.js. We have to know the root.
+function getServedPath(appPackageJson) {
+  const publicUrl = getPublicUrl(appPackageJson);
+  const servedUrl = envPublicUrl || (publicUrl ? url.parse(publicUrl).pathname : '/');
+  return ensureSlash(servedUrl, true);
+}
+
+const moduleFileExtensions = [
+  'web.mjs',
+  'mjs',
+  'web.js',
+  'js',
+  'web.ts',
+  'ts',
+  'web.tsx',
+  'tsx',
+  'json',
+  'web.jsx',
+  'jsx',
+];
+
+// Resolve file paths in the same order as webpack
+const resolveModule = (resolveFn, filePath) => {
+  const extension = moduleFileExtensions.find(extension =>
+    fs.existsSync(resolveFn(`${filePath}.${extension}`)),
+  );
+
+  if (extension) {
+    return resolveFn(`${filePath}.${extension}`);
+  }
+
+  return resolveFn(`${filePath}.js`);
+};
+
+// config after eject: we're in ./config/
+module.exports = {
+  dotenv: resolveApp('.env'),
+  appPath: resolveApp('.'),
+  appBuild: resolveApp('build'),
+  appPublic: resolveApp('public'),
+  appHtml: resolveApp('public/index.html'),
+  appIndexJs: resolveModule(resolveApp, 'src/index'),
+  appPackageJson: resolveApp('package.json'),
+  appSrc: resolveApp('src'),
+  appTsConfig: resolveApp('tsconfig.json'),
+  yarnLockFile: resolveApp('yarn.lock'),
+  testsSetup: resolveModule(resolveApp, 'src/setupTests'),
+  proxySetup: resolveApp('src/setupProxy.js'),
+  appNodeModules: resolveApp('node_modules'),
+  publicUrl: getPublicUrl(resolveApp('package.json')),
+  servedPath: getServedPath(resolveApp('package.json')),
+};
+
+module.exports.moduleFileExtensions = moduleFileExtensions;