get4prince / weatherapp

This project was bootstrapped with Create React App.

Below you will find some information on how to perform common tasks.
You can find the most recent version of this guide here.

Create React App is divided into two packages:

• create-react-app is a global command-line utility that you use to create new projects.
• react-scripts is a development dependency in the generated projects (including this one).

You almost never need to update create-react-app itself: it delegates all the setup to react-scripts.

When you run create-react-app, it always creates the project with the latest version of react-scripts so you’ll get all the new features and improvements in newly created apps automatically.

To update an existing project to a new version of react-scripts, open the changelog, find the version you’re currently on (check package.json in this folder if you’re not sure), and apply the migration instructions for the newer versions.

In most cases bumping the react-scripts version in package.json and running npm install in this folder should be enough, but it’s good to consult the changelog for potential breaking changes.

We commit to keeping the breaking changes minimal so you can upgrade react-scripts painlessly.

Available Scripts

In the project directory you can run:

npm start

Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

npm test

Launches the test runner in the interactive watch mode.
See the section about running tests for more information.

npm run build

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed.

See the section about deployment for more information.

npm run eject

Note: this is a one-way operation. Once you eject, you can’t go back!

If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.

Instead, it will copy all the configuration files and the transitive dependencies (Webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.

You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.

Testing Components

There is a broad spectrum of component testing techniques. They range from a “smoke test” verifying that a component renders without throwing, to shallow rendering and testing some of the output, to full rendering and testing component lifecycle and state changes.

Different projects choose different testing tradeoffs based on how often components change, and how much logic they contain. If you haven’t decided on a testing strategy yet, we recommend that you start with creating simple smoke tests for your components:

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

it('renders without crashing', () => {
  const div = document.createElement('div');
  ReactDOM.render(<App />, div);
});

This test mounts a component and makes sure that it didn’t throw during rendering. Tests like this provide a lot of value with very little effort so they are great as a starting point, and this is the test you will find in src/App.test.js.

When you encounter bugs caused by changing components, you will gain a deeper insight into which parts of them are worth testing in your application. This might be a good time to introduce more specific tests asserting specific expected output or behavior.

If you’d like to test components in isolation from the child components they render, we recommend using shallow() rendering API from Enzyme. To install it, run:

npm install --save enzyme enzyme-adapter-react-16 react-test-renderer

Alternatively you may use yarn:

yarn add enzyme enzyme-adapter-react-16 react-test-renderer

As of Enzyme 3, you will need to install Enzyme along with an Adapter corresponding to the version of React you are using. (The examples above use the adapter for React 16.)

The adapter will also need to be configured in your global setup file:

src/setupTests.js

import { configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({ adapter: new Adapter() });

Note: Keep in mind that if you decide to "eject" before creating src/setupTests.js, the resulting package.json file won't contain any reference to it. Read here to learn how to add this after ejecting.

Now you can write a smoke test with it:

import React from 'react';
import { shallow } from 'enzyme';
import App from './App';

it('renders without crashing', () => {
  shallow(<App />);
});

Unlike the previous smoke test using ReactDOM.render(), this test only renders <App> and doesn’t go deeper. For example, even if <App> itself renders a <Button> that throws, this test will pass. Shallow rendering is great for isolated unit tests, but you may still want to create some full rendering tests to ensure the components integrate correctly. Enzyme supports full rendering with mount(), and you can also use it for testing state changes and component lifecycle.

You can read the Enzyme documentation for more testing techniques. Enzyme documentation uses Chai and Sinon for assertions but you don’t have to use them because Jest provides built-in expect() and jest.fn() for spies.

Here is an example from Enzyme documentation that asserts specific output, rewritten to use Jest matchers:

import React from 'react';
import { shallow } from 'enzyme';
import App from './App';

it('renders welcome message', () => {
  const wrapper = shallow(<App />);
  const welcome = <h2>Welcome to React</h2>;
  // expect(wrapper.contains(welcome)).to.equal(true);
  expect(wrapper.contains(welcome)).toEqual(true);
});

All Jest matchers are extensively documented here.
Nevertheless you can use a third-party assertion library like Chai if you want to, as described below.

Additionally, you might find jest-enzyme helpful to simplify your tests with readable matchers. The above contains code can be written more simply with jest-enzyme.

expect(wrapper).toContainReact(welcome)

To enable this, install jest-enzyme:

npm install --save jest-enzyme

Alternatively you may use yarn:

yarn add jest-enzyme

Import it in src/setupTests.js to make its matchers available in every test:

import 'jest-enzyme';

Using Third Party Assertion Libraries

We recommend that you use expect() for assertions and jest.fn() for spies. If you are having issues with them please file those against Jest, and we’ll fix them. We intend to keep making them better for React, supporting, for example, pretty-printing React elements as JSX.

However, if you are used to other libraries, such as Chai and Sinon, or if you have existing code using them that you’d like to port over, you can import them normally like this:

import sinon from 'sinon';
import { expect } from 'chai';

and then use them in your tests like you normally do.

Initializing Test Environment

Note: this feature is available with react-scripts@0.4.0 and higher.

If your app uses a browser API that you need to mock in your tests or if you just need a global setup before running your tests, add a src/setupTests.js to your project. It will be automatically executed before running your tests.

For example:

src/setupTests.js

const localStorageMock = {
  getItem: jest.fn(),
  setItem: jest.fn(),
  clear: jest.fn()
};
global.localStorage = localStorageMock

Note: Keep in mind that if you decide to "eject" before creating src/setupTests.js, the resulting package.json file won't contain any reference to it, so you should manually create the property setupTestFrameworkScriptFile in the configuration for Jest, something like the following:

"jest": {
  // ...
  "setupTestFrameworkScriptFile": "<rootDir>/src/setupTests.js"
 }

Focusing and Excluding Tests

You can replace it() with xit() to temporarily exclude a test from being executed.
Similarly, fit() lets you focus on a specific test without running any other tests.

Coverage Reporting

Jest has an integrated coverage reporter that works well with ES6 and requires no configuration.
Run npm test -- --coverage (note extra -- in the middle) to include a coverage report like this:

Note that tests run much slower with coverage so it is recommended to run it separately from your normal workflow.

Configuration

The default Jest coverage configuration can be overriden by adding any of the following supported keys to a Jest config in your package.json.

Supported overrides:

• collectCoverageFrom
• coverageReporters
• coverageThreshold
• snapshotSerializers

Example package.json:

{
  "name": "your-package",
  "jest": {
    "collectCoverageFrom" : [
      "src/**/*.{js,jsx}",
      "!<rootDir>/node_modules/",
      "!<rootDir>/path/to/dir/"
    ],
    "coverageThreshold": {
      "global": {
        "branches": 90,
        "functions": 90,
        "lines": 90,
        "statements": 90
      }
    },
    "coverageReporters": ["text"],
    "snapshotSerializers": ["my-serializer-module"]
  }
}

Continuous Integration

By default npm test runs the watcher with interactive CLI. However, you can force it to run tests once and finish the process by setting an environment variable called CI.

When creating a build of your application with npm run build linter warnings are not checked by default. Like npm test, you can force the build to perform a linter warning check by setting the environment variable CI. If any warnings are encountered then the build fails.

Popular CI servers already set the environment variable CI by default but you can do this yourself too:

On CI servers

Travis CI

1. Following the Travis Getting started guide for syncing your GitHub repository with Travis. You may need to initialize some settings manually in your profile page.
2. Add a .travis.yml file to your git repository.

language: node_js
node_js:
  - 6
cache:
  directories:
    - node_modules
script:
  - npm run build
  - npm test

1. Trigger your first build with a git push.
2. Customize your Travis CI Build if needed.

CircleCI

Follow this article to set up CircleCI with a Create React App project.

On your own environment

Windows (cmd.exe)

set CI=true&&npm test

set CI=true&&npm run build

(Note: the lack of whitespace is intentional.)

Windows (Powershell)

($env:CI = $true) -and (npm test)

($env:CI = $true) -and (npm run build)

Linux, macOS (Bash)

CI=true npm test

CI=true npm run build

The test command will force Jest to run tests once instead of launching the watcher.

If you find yourself doing this often in development, please file an issue to tell us about your use case because we want to make watcher the best experience and are open to changing how it works to accommodate more workflows.

The build command will check for linter warnings and fail if any are found.

Disabling jsdom

By default, the package.json of the generated project looks like this:

  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test --env=jsdom"

If you know that none of your tests depend on jsdom, you can safely remove --env=jsdom, and your tests will run faster:

  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
-   "test": "react-scripts test --env=jsdom"
+   "test": "react-scripts test"

To help you make up your mind, here is a list of APIs that need jsdom:

• Any browser globals like window and document
• ReactDOM.render()
• TestUtils.renderIntoDocument() (a shortcut for the above)
• mount() in Enzyme

In contrast, jsdom is not needed for the following APIs:

• TestUtils.createRenderer() (shallow rendering)
• shallow() in Enzyme

Finally, jsdom is also not needed for snapshot testing.

Snapshot Testing

Snapshot testing is a feature of Jest that automatically generates text snapshots of your components and saves them on the disk so if the UI output changes, you get notified without manually writing any assertions on the component output. Read more about snapshot testing.

Editor Integration

If you use Visual Studio Code, there is a Jest extension which works with Create React App out of the box. This provides a lot of IDE-like features while using a text editor: showing the status of a test run with potential fail messages inline, starting and stopping the watcher automatically, and offering one-click snapshot updates.

Debugging Tests

There are various ways to setup a debugger for your Jest tests. We cover debugging in Chrome and Visual Studio Code.

Note: debugging tests requires Node 8 or higher.

Debugging Tests in Chrome

Add the following to the scripts section in your project's package.json

"scripts": {
    "test:debug": "react-scripts --inspect-brk test --runInBand --env=jsdom"
  }

Place debugger; statements in any test and run:

$ npm run test:debug

This will start running your Jest tests, but pause before executing to allow a debugger to attach to the process.

Open the following in Chrome

about:inspect

After opening that link, the Chrome Developer Tools will be displayed. Select inspect on your process and a breakpoint will be set at the first line of the react script (this is done simply to give you time to open the developer tools and to prevent Jest from executing before you have time to do so). Click the button that looks like a "play" button in the upper right hand side of the screen to continue execution. When Jest executes the test that contains the debugger statement, execution will pause and you can examine the current scope and call stack.

Note: the --runInBand cli option makes sure Jest runs test in the same process rather than spawning processes for individual tests. Normally Jest parallelizes test runs across processes but it is hard to debug many processes at the same time.

Debugging Tests in Visual Studio Code

Debugging Jest tests is supported out of the box for Visual Studio Code.

Use the following launch.json configuration file:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Debug CRA Tests",
      "type": "node",
      "request": "launch",
      "runtimeExecutable": "${workspaceRoot}/node_modules/.bin/react-scripts",      
      "args": [
        "test",
        "--runInBand",
        "--no-cache",
        "--env=jsdom"
      ],
      "cwd": "${workspaceRoot}",
      "protocol": "inspector",
      "console": "integratedTerminal",
      "internalConsoleOptions": "neverOpen"
    }
  ]
}

Developing Components in Isolation

Usually, in an app, you have a lot of UI components, and each of them has many different states. For an example, a simple button component could have following states:

• In a regular state, with a text label.
• In the disabled mode.
• In a loading state.

Usually, it’s hard to see these states without running a sample app or some examples.

Create React App doesn’t include any tools for this by default, but you can easily add Storybook for React (source) or React Styleguidist (source) to your project. These are third-party tools that let you develop components and see all their states in isolation from your app.

You can also deploy your Storybook or style guide as a static app. This way, everyone in your team can view and review different states of UI components without starting a backend server or creating an account in your app.

Getting Started with Storybook

Storybook is a development environment for React UI components. It allows you to browse a component library, view the different states of each component, and interactively develop and test components.

First, install the following npm package globally:

npm install -g @storybook/cli

Then, run the following command inside your app’s directory:

getstorybook

After that, follow the instructions on the screen.

Learn More About React Storybook:

• Screencast: Getting Started with React Storybook
• GitHub Repo
• Documentation
• Snapshot Testing UI with Storybook + addon/storyshot

Getting Started with Styleguidist

Styleguidist combines a style guide, where all your components are presented on a single page with their props documentation and usage examples, with an environment for developing components in isolation, similar to Storybook. In Styleguidist you write examples in Markdown, where each code snippet is rendered as a live editable playground.

First, install Styleguidist:

npm install --save react-styleguidist

Alternatively you may use yarn:

yarn add react-styleguidist

Then, add these scripts to your package.json:

   "scripts": {
+    "styleguide": "styleguidist server",
+    "styleguide:build": "styleguidist build",
     "start": "react-scripts start",

Then, run the following command inside your app’s directory:

npm run styleguide

After that, follow the instructions on the screen.

Learn more about React Styleguidist:

• GitHub Repo
• Documentation

Publishing Components to npm

Create React App doesn't provide any built-in functionality to publish a component to npm. If you're ready to extract a component from your project so other people can use it, we recommend moving it to a separate directory outside of your project and then using a tool like nwb to prepare it for publishing.

Making a Progressive Web App

By default, the production build is a fully functional, offline-first Progressive Web App.

Progressive Web Apps are faster and more reliable than traditional web pages, and provide an engaging mobile experience:

• All static site assets are cached so that your page loads fast on subsequent visits, regardless of network connectivity (such as 2G or 3G). Updates are downloaded in the background.
• Your app will work regardless of network state, even if offline. This means your users will be able to use your app at 10,000 feet and on the subway.
• On mobile devices, your app can be added directly to the user's home screen, app icon and all. You can also re-engage users using web push notifications. This eliminates the need for the app store.

The sw-precache-webpack-plugin is integrated into production configuration, and it will take care of generating a service worker file that will automatically precache all of your local assets and keep them up to date as you deploy updates. The service worker will use a cache-first strategy for handling all requests for local assets, including the initial HTML, ensuring that your web app is reliably fast, even on a slow or unreliable network.

Opting Out of Caching

If you would prefer not to enable service workers prior to your initial production deployment, then remove the call to registerServiceWorker() from src/index.js.

If you had previously enabled service workers in your production deployment and have decided that you would like to disable them for all your existing users, you can swap out the call to registerServiceWorker() in src/index.js first by modifying the service worker import:

import { unregister } from './registerServiceWorker';

and then call unregister() instead. After the user visits a page that has unregister(), the service worker will be uninstalled. Note that depending on how /service-worker.js is served, it may take up to 24 hours for the cache to be invalidated.

Offline-First Considerations

1. Service workers require HTTPS, although to facilitate local testing, that policy does not apply to localhost. If your production web server does not support HTTPS, then the service worker registration will fail, but the rest of your web app will remain functional.

2. Service workers are not currently supported in all web browsers. Service worker registration won't be attempted on browsers that lack support.

3. The service worker is only enabled in the production environment, e.g. the output of npm run build. It's recommended that you do not enable an offline-first service worker in a development environment, as it can lead to frustration when previously cached assets are used and do not include the latest changes you've made locally.

4. If you need to test your offline-first service worker locally, build the application (using npm run build) and run a simple http server from your build directory. After running the build script, create-react-app will give instructions for one way to test your production build locally and the deployment instructions have instructions for using other methods. Be sure to always use an incognito window to avoid complications with your browser cache.

5. If possible, configure your production environment to serve the generated service-worker.js with HTTP caching disabled. If that's not possible—GitHub Pages, for instance, does not allow you to change the default 10 minute HTTP cache lifetime—then be aware that if you visit your production site, and then revisit again before service-worker.js has expired from your HTTP cache, you'll continue to get the previously cached assets from the service worker. If you have an immediate need to view your updated production deployment, performing a shift-refresh will temporarily disable the service worker and retrieve all assets from the network.

6. Users aren't always familiar with offline-first web apps. It can be useful to let the user know when the service worker has finished populating your caches (showing a "This web app works offline!" message) and also let them know when the service worker has fetched the latest updates that will be available the next time they load the page (showing a "New content is available; please refresh." message). Showing this messages is currently left as an exercise to the developer, but as a starting point, you can make use of the logic included in src/registerServiceWorker.js, which demonstrates which service worker lifecycle events to listen for to detect each scenario, and which as a default, just logs appropriate messages to the JavaScript console.

7. By default, the generated service worker file will not intercept or cache any cross-origin traffic, like HTTP API requests, images, or embeds loaded from a different domain. If you would like to use a runtime caching strategy for those requests, you can eject and then configure the runtimeCaching option in the SWPrecacheWebpackPlugin section of webpack.config.prod.js.

Progressive Web App Metadata

The default configuration includes a web app manifest located at public/manifest.json, that you can customize with details specific to your web application.

When a user adds a web app to their homescreen using Chrome or Firefox on Android, the metadata in manifest.json determines what icons, names, and branding colors to use when the web app is displayed. The Web App Manifest guide provides more context about what each field means, and how your customizations will affect your users' experience.

Analyzing the Bundle Size

Source map explorer analyzes JavaScript bundles using the source maps. This helps you understand where code bloat is coming from.

To add Source map explorer to a Create React App project, follow these steps:

npm install --save source-map-explorer

Alternatively you may use yarn:

yarn add source-map-explorer

Then in package.json, add the following line to scripts:

   "scripts": {
+    "analyze": "source-map-explorer build/static/js/main.*",
     "start": "react-scripts start",
     "build": "react-scripts build",
     "test": "react-scripts test --env=jsdom",

Then to analyze the bundle run the production build then run the analyze script.

npm run build
npm run analyze

Deployment

npm run build creates a build directory with a production build of your app. Set up your favorite HTTP server so that a visitor to your site is served index.html, and requests to static paths like /static/js/main.<hash>.js are served with the contents of the /static/js/main.<hash>.js file.

Static Server

For environments using Node, the easiest way to handle this would be to install serve and let it handle the rest:

npm install -g serve
serve -s build

The last command shown above will serve your static site on the port 5000. Like many of serve’s internal settings, the port can be adjusted using the -p or --port flags.

Run this command to get a full list of the options available:

serve -h

Other Solutions

You don’t necessarily need a static server in order to run a Create React App project in production. It works just as fine integrated into an existing dynamic one.

Here’s a programmatic example using Node and Express:

const express = require('express');
const path = require('path');
const app = express();

app.use(express.static(path.join(__dirname, 'build')));

app.get('/', function (req, res) {
  res.sendFile(path.join(__dirname, 'build', 'index.html'));
});

app.listen(9000);

The choice of your server software isn’t important either. Since Create React App is completely platform-agnostic, there’s no need to explicitly use Node.

The build folder with static assets is the only output produced by Create React App.

However this is not quite enough if you use client-side routing. Read the next section if you want to support URLs like /todos/42 in your single-page app.

Serving Apps with Client-Side Routing

If you use routers that use the HTML5 pushState history API under the hood (for example, React Router with browserHistory), many static file servers will fail. For example, if you used React Router with a route for /todos/42, the development server will respond to localhost:3000/todos/42 properly, but an Express serving a production build as above will not.

This is because when there is a fresh page load for a /todos/42, the server looks for the file build/todos/42 and does not find it. The server needs to be configured to respond to a request to /todos/42 by serving index.html. For example, we can amend our Express example above to serve index.html for any unknown paths:

 app.use(express.static(path.join(__dirname, 'build')));

-app.get('/', function (req, res) {
+app.get('/*', function (req, res) {
   res.sendFile(path.join(__dirname, 'build', 'index.html'));
 });

If you’re using Apache HTTP Server, you need to create a .htaccess file in the public folder that looks like this:

    Options -MultiViews
    RewriteEngine On
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^ index.html [QSA,L]

It will get copied to the build folder when you run npm run build.

If you’re using Apache Tomcat, you need to follow this Stack Overflow answer.

Now requests to /todos/42 will be handled correctly both in development and in production.

On a production build, and in a browser that supports service workers, the service worker will automatically handle all navigation requests, like for /todos/42, by serving the cached copy of your index.html. This service worker navigation routing can be configured or disabled by ejecting and then modifying the navigateFallback and navigateFallbackWhitelist options of the SWPreachePlugin configuration.

When users install your app to the homescreen of their device the default configuration will make a shortcut to /index.html. This may not work for client-side routers which expect the app to be served from /. Edit the web app manifest at public/manifest.json and change start_url to match the required URL scheme, for example:

  "start_url": ".",

Building for Relative Paths

By default, Create React App produces a build assuming your app is hosted at the server root.
To override this, specify the homepage in your package.json, for example:

  "homepage": "http://mywebsite.com/relativepath",

This will let Create React App correctly infer the root path to use in the generated HTML file.

Note: If you are using react-router@^4, you can root <Link>s using the basename prop on any <Router>.
More information here.

For example:

<BrowserRouter basename="/calendar"/>
<Link to="/today"/> // renders <a href="/calendar/today">

Serving the Same Build from Different Paths

Note: this feature is available with react-scripts@0.9.0 and higher.

If you are not using the HTML5 pushState history API or not using client-side routing at all, it is unnecessary to specify the URL from which your app will be served. Instead, you can put this in your package.json:

  "homepage": ".",

This will make sure that all the asset paths are relative to index.html. You will then be able to move your app from http://mywebsite.com to http://mywebsite.com/relativepath or even http://mywebsite.com/relative/path without having to rebuild it.

Azure

See this blog post on how to deploy your React app to Microsoft Azure.

See this blog post or this repo for a way to use automatic deployment to Azure App Service.

Firebase

Install the Firebase CLI if you haven’t already by running npm install -g firebase-tools. Sign up for a Firebase account and create a new project. Run firebase login and login with your previous created Firebase account.

Then run the firebase init command from your project’s root. You need to choose the Hosting: Configure and deploy Firebase Hosting sites and choose the Firebase project you created in the previous step. You will need to agree with database.rules.json being created, choose build as the public directory, and also agree to Configure as a single-page app by replying with y.

    === Project Setup

    First, let's associate this project directory with a Firebase project.
    You can create multiple project aliases by running firebase use --add,
    but for now we'll just set up a default project.

    ? What Firebase project do you want to associate as default? Example app (example-app-fd690)

    === Database Setup

    Firebase Realtime Database Rules allow you to define how your data should be
    structured and when your data can be read from and written to.

    ? What file should be used for Database Rules? database.rules.json
    ✔  Database Rules for example-app-fd690 have been downloaded to database.rules.json.
    Future modifications to database.rules.json will update Database Rules when you run
    firebase deploy.

    === Hosting Setup

    Your public directory is the folder (relative to your project directory) that
    will contain Hosting assets to uploaded with firebase deploy. If you
    have a build process for your assets, use your build's output directory.

    ? What do you want to use as your public directory? build
    ? Configure as a single-page app (rewrite all urls to /index.html)? Yes
    ✔  Wrote build/index.html

    i  Writing configuration info to firebase.json...
    i  Writing project information to .firebaserc...

    ✔  Firebase initialization complete!

IMPORTANT: you need to set proper HTTP caching headers for service-worker.js file in firebase.json file or you will not be able to see changes after first deployment (issue #2440). It should be added inside "hosting" key like next:

{
  "hosting": {
    ...
    "headers": [
      {"source": "/service-worker.js", "headers": [{"key": "Cache-Control", "value": "no-cache"}]}
    ]
    ...

Now, after you create a production build with npm run build, you can deploy it by running firebase deploy.

    === Deploying to 'example-app-fd690'...

    i  deploying database, hosting
    ✔  database: rules ready to deploy.
    i  hosting: preparing build directory for upload...
    Uploading: [==============================          ] 75%✔  hosting: build folder uploaded successfully
    ✔  hosting: 8 files uploaded successfully
    i  starting release process (may take several minutes)...

    ✔  Deploy complete!

    Project Console: https://console.firebase.google.com/project/example-app-fd690/overview
    Hosting URL: https://example-app-fd690.firebaseapp.com

For more information see Add Firebase to your JavaScript Project.

GitHub Pages

Note: this feature is available with react-scripts@0.2.0 and higher.

Step 1: Add homepage to package.json

The step below is important!
If you skip it, your app will not deploy correctly.

Open your package.json and add a homepage field for your project:

  "homepage": "https://myusername.github.io/my-app",

or for a GitHub user page:

  "homepage": "https://myusername.github.io",

Create React App uses the homepage field to determine the root URL in the built HTML file.

Step 2: Install gh-pages and add deploy to scripts in package.json

Now, whenever you run npm run build, you will see a cheat sheet with instructions on how to deploy to GitHub Pages.

To publish it at https://myusername.github.io/my-app, run:

npm install --save gh-pages

Alternatively you may use yarn:

yarn add gh-pages

Add the following scripts in your package.json:

  "scripts": {
+   "predeploy": "npm run build",
+   "deploy": "gh-pages -d build",
    "start": "react-scripts start",
    "build": "react-scripts build",

The predeploy script will run automatically before deploy is run.

If you are deploying to a GitHub user page instead of a project page you'll need to make two additional modifications:

1. First, change your repository's source branch to be any branch other than master.
2. Additionally, tweak your package.json scripts to push deployments to master:

  "scripts": {
    "predeploy": "npm run build",
-   "deploy": "gh-pages -d build",
+   "deploy": "gh-pages -b master -d build",

Step 3: Deploy the site by running npm run deploy

Then run:

npm run deploy

Step 4: Ensure your project’s settings use gh-pages

Finally, make sure GitHub Pages option in your GitHub project settings is set to use the gh-pages branch:

Step 5: Optionally, configure the domain

You can configure a custom domain with GitHub Pages by adding a CNAME file to the public/ folder.

Notes on client-side routing

GitHub Pages doesn’t support routers that use the HTML5 pushState history API under the hood (for example, React Router using browserHistory). This is because when there is a fresh page load for a url like http://user.github.io/todomvc/todos/42, where /todos/42 is a frontend route, the GitHub Pages server returns 404 because it knows nothing of /todos/42. If you want to add a router to a project hosted on GitHub Pages, here are a couple of solutions:

• You could switch from using HTML5 history API to routing with hashes. If you use React Router, you can switch to hashHistory for this effect, but the URL will be longer and more verbose (for example, http://user.github.io/todomvc/#/todos/42?_k=yknaj). Read more about different history implementations in React Router.
• Alternatively, you can use a trick to teach GitHub Pages to handle 404 by redirecting to your index.html page with a special redirect parameter. You would need to add a 404.html file with the redirection code to the build folder before deploying your project, and you’ll need to add code handling the redirect parameter to index.html. You can find a detailed explanation of this technique in this guide.

Troubleshooting

"/dev/tty: No such a device or address"

If, when deploying, you get /dev/tty: No such a device or address or a similar error, try the follwing:

1. Create a new Personal Access Token
2. git remote set-url origin https://<user>:<token>@github.com/<user>/<repo> .
3. Try npm run deploy again

Heroku

Use the Heroku Buildpack for Create React App.
You can find instructions in Deploying React with Zero Configuration.

Resolving Heroku Deployment Errors

Sometimes npm run build works locally but fails during deploy via Heroku. Following are the most common cases.

"Module not found: Error: Cannot resolve 'file' or 'directory'"

If you get something like this:

remote: Failed to create a production build. Reason:
remote: Module not found: Error: Cannot resolve 'file' or 'directory'
MyDirectory in /tmp/build_1234/src

It means you need to ensure that the lettercase of the file or directory you import matches the one you see on your filesystem or on GitHub.

This is important because Linux (the operating system used by Heroku) is case sensitive. So MyDirectory and mydirectory are two distinct directories and thus, even though the project builds locally, the difference in case breaks the import statements on Heroku remotes.

"Could not find a required file."

If you exclude or ignore necessary files from the package you will see a error similar this one:

remote: Could not find a required file.
remote:   Name: `index.html`
remote:   Searched in: /tmp/build_a2875fc163b209225122d68916f1d4df/public
remote:
remote: npm ERR! Linux 3.13.0-105-generic
remote: npm ERR! argv "/tmp/build_a2875fc163b209225122d68916f1d4df/.heroku/node/bin/node" "/tmp/build_a2875fc163b209225122d68916f1d4df/.heroku/node/bin/npm" "run" "build"

In this case, ensure that the file is there with the proper lettercase and that’s not ignored on your local .gitignore or ~/.gitignore_global.

Netlify

To do a manual deploy to Netlify’s CDN:

npm install netlify-cli -g
netlify deploy

Choose build as the path to deploy.

To setup continuous delivery:

With this setup Netlify will build and deploy when you push to git or open a pull request:

1. Start a new netlify project
2. Pick your Git hosting service and select your repository
3. Set yarn build as the build command and build as the publish directory
4. Click Deploy site

Support for client-side routing:

To support pushState, make sure to create a public/_redirects file with the following rewrite rules:

/*  /index.html  200

When you build the project, Create React App will place the public folder contents into the build output.

Now

Now offers a zero-configuration single-command deployment. You can use now to deploy your app for free.

1. Install the now command-line tool either via the recommended desktop tool or via node with npm install -g now.

2. Build your app by running npm run build.

3. Move into the build directory by running cd build.

4. Run now --name your-project-name from within the build directory. You will see a now.sh URL in your output like this:

   > Ready! https://your-project-name-tpspyhtdtk.now.sh (copied to clipboard)
   

   Paste that URL into your browser when the build is complete, and you will see your deployed app.

Details are available in this article.

S3 and CloudFront

See this blog post on how to deploy your React app to Amazon Web Services S3 and CloudFront.

Surge

Install the Surge CLI if you haven’t already by running npm install -g surge. Run the surge command and log in you or create a new account.

When asked about the project path, make sure to specify the build folder, for example:

       project path: /path/to/project/build

Note that in order to support routers that use HTML5 pushState API, you may want to rename the index.html in your build folder to 200.html before deploying to Surge. This ensures that every URL falls back to that file.

Advanced Configuration

You can adjust various development and production settings by setting environment variables in your shell or with .env.

Variable	Development	Production	Usage
BROWSER	✅	❌	By default, Create React App will open the default system browser, favoring Chrome on macOS. Specify a browser to override this behavior, or set it to none to disable it completely. If you need to customize the way the browser is launched, you can specify a node script instead. Any arguments passed to npm start will also be passed to this script, and the url where your app is served will be the last argument. Your script's file name must have the .js extension.
HOST	✅	❌	By default, the development web server binds to localhost. You may use this variable to specify a different host.
PORT	✅	❌	By default, the development web server will attempt to listen on port 3000 or prompt you to attempt the next available port. You may use this variable to specify a different port.
HTTPS	✅	❌	When set to true, Create React App will run the development server in https mode.
PUBLIC_URL	❌	✅	Create React App assumes your application is hosted at the serving web server's root or a subpath as specified in package.json (homepage). Normally, Create React App ignores the hostname. You may use this variable to force assets to be referenced verbatim to the url you provide (hostname included). This may be particularly useful when using a CDN to host your application.
CI	🔶	✅	When set to true, Create React App treats warnings as failures in the build. It also makes the test runner non-watching. Most CIs set this flag by default.
REACT_EDITOR	✅	❌	When an app crashes in development, you will see an error overlay with clickable stack trace. When you click on it, Create React App will try to determine the editor you are using based on currently running processes, and open the relevant source file. You can send a pull request to detect your editor of choice. Setting this environment variable overrides the automatic detection. If you do it, make sure your systems PATH environment variable points to your editor’s bin folder. You can also set it to none to disable it completely.
CHOKIDAR_USEPOLLING	✅	❌	When set to true, the watcher runs in polling mode, as necessary inside a VM. Use this option if npm start isn't detecting changes.
GENERATE_SOURCEMAP	❌	✅	When set to false, source maps are not generated for a production build. This solves OOM issues on some smaller machines.
NODE_PATH	✅	✅	Same as NODE_PATH in Node.js, but only relative folders are allowed. Can be handy for emulating a monorepo setup by setting NODE_PATH=src.

Troubleshooting

npm start doesn’t detect changes

When you save a file while npm start is running, the browser should refresh with the updated code.
If this doesn’t happen, try one of the following workarounds:

• If your project is in a Dropbox folder, try moving it out.
• If the watcher doesn’t see a file called index.js and you’re referencing it by the folder name, you need to restart the watcher due to a Webpack bug.
• Some editors like Vim and IntelliJ have a “safe write” feature that currently breaks the watcher. You will need to disable it. Follow the instructions in “Adjusting Your Text Editor”.
• If your project path contains parentheses, try moving the project to a path without them. This is caused by a Webpack watcher bug.
• On Linux and macOS, you might need to tweak system settings to allow more watchers.
• If the project runs inside a virtual machine such as (a Vagrant provisioned) VirtualBox, create an .env file in your project directory if it doesn’t exist, and add CHOKIDAR_USEPOLLING=true to it. This ensures that the next time you run npm start, the watcher uses the polling mode, as necessary inside a VM.

If none of these solutions help please leave a comment in this thread.

npm test hangs on macOS Sierra

If you run npm test and the console gets stuck after printing react-scripts test --env=jsdom to the console there might be a problem with your Watchman installation as described in facebookincubator/create-react-app#713.

We recommend deleting node_modules in your project and running npm install (or yarn if you use it) first. If it doesn't help, you can try one of the numerous workarounds mentioned in these issues:

• facebook/jest#1767
• facebook/watchman#358
• ember-cli/ember-cli#6259

It is reported that installing Watchman 4.7.0 or newer fixes the issue. If you use Homebrew, you can run these commands to update it:

watchman shutdown-server
brew update
brew reinstall watchman

You can find other installation methods on the Watchman documentation page.

If this still doesn’t help, try running launchctl unload -F ~/Library/LaunchAgents/com.github.facebook.watchman.plist.

There are also reports that uninstalling Watchman fixes the issue. So if nothing else helps, remove it from your system and try again.

npm run build exits too early

It is reported that npm run build can fail on machines with limited memory and no swap space, which is common in cloud environments. Even with small projects this command can increase RAM usage in your system by hundreds of megabytes, so if you have less than 1 GB of available memory your build is likely to fail with the following message:

The build failed because the process exited too early. This probably means the system ran out of memory or someone called kill -9 on the process.

If you are completely sure that you didn't terminate the process, consider adding some swap space to the machine you’re building on, or build the project locally.

npm run build fails on Heroku

This may be a problem with case sensitive filenames. Please refer to this section.

Moment.js locales are missing

If you use a Moment.js, you might notice that only the English locale is available by default. This is because the locale files are large, and you probably only need a subset of all the locales provided by Moment.js.

To add a specific Moment.js locale to your bundle, you need to import it explicitly.
For example:

import moment from 'moment';
import 'moment/locale/fr';

If import multiple locales this way, you can later switch between them by calling moment.locale() with the locale name:

import moment from 'moment';
import 'moment/locale/fr';
import 'moment/locale/es';

// ...

moment.locale('fr');

This will only work for locales that have been explicitly imported before.

npm run build fails to minify

Some third-party packages don't compile their code to ES5 before publishing to npm. This often causes problems in the ecosystem because neither browsers (except for most modern versions) nor some tools currently support all ES6 features. We recommend to publish code on npm as ES5 at least for a few more years.

To resolve this:

1. Open an issue on the dependency's issue tracker and ask that the package be published pre-compiled.

• Note: Create React App can consume both CommonJS and ES modules. For Node.js compatibility, it is recommended that the main entry point is CommonJS. However, they can optionally provide an ES module entry point with the module field in package.json. Note that even if a library provides an ES Modules version, it should still precompile other ES6 features to ES5 if it intends to support older browsers.

2. Fork the package and publish a corrected version yourself.

3. If the dependency is small enough, copy it to your src/ folder and treat it as application code.

In the future, we might start automatically compiling incompatible third-party modules, but it is not currently supported. This approach would also slow down the production builds.

Alternatives to Ejecting

Ejecting lets you customize anything, but from that point on you have to maintain the configuration and scripts yourself. This can be daunting if you have many similar projects. In such cases instead of ejecting we recommend to fork react-scripts and any other packages you need. This article dives into how to do it in depth. You can find more discussion in this issue.

Something Missing?

If you have ideas for more “How To” recipes that should be on this page, let us know or contribute some!