Merge pull request #42 from leeor/master

Implementation using redux-serial-effects

Author: slorber

redux-serial-effects/.gitignore

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+# See https://help.github.com/ignore-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+
+# testing
+/coverage
+
+# production
+/build
+
+# misc
+.DS_Store
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

redux-serial-effects/README.md

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+## Scalable Frontend with Redux and `redux-serial-effects`
+
+An implementation based on [redux-serial-effects](https://github.com/wix/redux-serial-effects).
+
+`redux-serial-effects` is a middleware for handling side-effects. It listens for state changes and
+allows the composition of `subscriber`s, in a similar fashion as `reducers`s, that handle the
+invocation of side-effects as required by the changes in state.
+
+In complex apps these `subscriber`s can query 3rd party services and compare the outside world's
+state against the internal app state as the basis for deciding on the side-effects needed to sync
+the two (actual vs. expected state).
+
+In this simple implementation, the Gif `subscriber` is listening on requests for a new Gif based on
+comparing the previous state and the current one, and then triggers a fetch. It doesn't currently
+handle failures, but that could easily be accomplished with another action it'll fire that will
+update the state into retry mode.
+
+Since both the `reducer` and `subscriber` are equally composable, making the Gif component itself
+composable enables us to reuse it easily in all the randomGif components required by this spec. The
+component is made composable by supplying it with a state `selector` that passes only the relevant
+state slice to each instance, and an action `designator` that wraps dispatch for sending actions
+triggered by each copy only to its own reducer.
+
+A small utility is then used to easily make this component both relocatable in the state tree and
+repeatable (`encapsulateComponent`). For a real application, this helper should be split into
+`relocatableComponent` and `repeatableComponent` helpers.
+
+The counter value is managed by an `onNewGifRequested` handler passed to each Gif instance. It can
+also be implemented as a reducer/subscriber where the reducer listens to all NEW_GIF actions,
+regardless of the Gif instance that triggered them, and then signals the reducer how the counter
+should be incremented. The reducer will then dispatch the correct increment action.

redux-serial-effects/config/env.js

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+'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.
+// https://github.com/motdotla/dotenv
+dotenvFiles.forEach(dotenvFile => {
+  if (fs.existsSync(dotenvFile)) {
+    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/facebookincubator/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/facebookincubator/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;

redux-serial-effects/config/paths.js

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+'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/facebookincubator/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(path, needsSlash) {
+  const hasSlash = path.endsWith('/');
+  if (hasSlash && !needsSlash) {
+    return path.substr(path, path.length - 1);
+  } else if (!hasSlash && needsSlash) {
+    return `${path}/`;
+  } else {
+    return path;
+  }
+}
+
+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);
+}
+
+// config after eject: we're in ./config/
+module.exports = {
+  dotenv: resolveApp('.env'),
+  appBuild: resolveApp('build'),
+  appPublic: resolveApp('public'),
+  appHtml: resolveApp('public/index.html'),
+  appIndexJs: resolveApp('src/index.js'),
+  appPackageJson: resolveApp('package.json'),
+  appSrc: resolveApp('src'),
+  yarnLockFile: resolveApp('yarn.lock'),
+  testsSetup: resolveApp('src/setupTests.js'),
+  appNodeModules: resolveApp('node_modules'),
+  publicUrl: getPublicUrl(resolveApp('package.json')),
+  servedPath: getServedPath(resolveApp('package.json')),
+};

redux-serial-effects/config/polyfills.js

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+'use strict';
+
+if (typeof Promise === 'undefined') {
+  // Rejection tracking prevents a common issue where React gets into an
+  // inconsistent state due to an error, but it gets swallowed by a Promise,
+  // and the user has no idea what causes React's erratic future behavior.
+  require('promise/lib/rejection-tracking').enable();
+  window.Promise = require('promise/lib/es6-extensions.js');
+}
+
+// fetch() polyfill for making API calls.
+require('whatwg-fetch');
+
+// Object.assign() is commonly used with React.
+// It will use the native implementation if it's present and isn't buggy.
+Object.assign = require('object-assign');