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.

Table of Contents

• Updating to New Releases
• Sending Feedback
• Folder Structure
• Available Scripts
  • npm start
  • npm test
  • npm run build
  • npm run eject
• Supported Language Features and Polyfills
• Syntax Highlighting in the Editor
• Displaying Lint Output in the Editor
• Debugging in the Editor
• Changing the Page <title>
• Installing a Dependency
• Importing a Component
• Adding a Stylesheet
• Post-Processing CSS
• Adding a CSS Preprocessor (Sass, Less etc.)
• Adding Images and Fonts
• Using the public Folder
  • Changing the HTML
  • Adding Assets Outside of the Module System
  • When to Use the public Folder
• Using Global Variables
• Adding Bootstrap
  • Using a Custom Theme
• Adding Flow
• Adding Custom Environment Variables
  • Referencing Environment Variables in the HTML
  • Adding Temporary Environment Variables In Your Shell
  • Adding Development Environment Variables In .env
• Can I Use Decorators?
• Integrating with an API Backend
  • Node
  • Ruby on Rails
• Proxying API Requests in Development
• Using HTTPS in Development
• Generating Dynamic <meta> Tags on the Server
• Pre-Rendering into Static HTML Files
• Injecting Data from the Server into the Page
• Running Tests
  • Filename Conventions
  • Command Line Interface
  • Version Control Integration
  • Writing Tests
  • Testing Components
  • Using Third Party Assertion Libraries
  • Initializing Test Environment
  • Focusing and Excluding Tests
  • Coverage Reporting
  • Continuous Integration
  • Disabling jsdom
  • Snapshot Testing
  • Editor Integration
• Developing Components in Isolation
• Making a Progressive Web App
• Deployment
  • Serving Apps with Client-Side Routing
  • Building for Relative Paths
  • Azure
  • Firebase
  • GitHub Pages
  • Heroku
  • Modulus
  • Netlify
  • Now
  • S3 and CloudFront
  • Surge
• Advanced Configuration
• Troubleshooting
  • npm start doesn�t detect changes
  • npm test hangs on macOS Sierra
  • npm run build silently fails
  • npm run build fails on Heroku
• Something Missing?

Updating to New Releases

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.

Sending Feedback

We are always open to your feedback.

Folder Structure

After creation, your project should look like this:

my-app/
  README.md
  node_modules/
  package.json
  public/
    index.html
    favicon.ico
  src/
    App.css
    App.js
    App.test.js
    index.css
    index.js
    logo.svg

For the project to build, these files must exist with exact filenames:

• public/index.html is the page template;
• src/index.js is the JavaScript entry point.

You can delete or rename the other files.

You may create subdirectories inside src. For faster rebuilds, only files inside src are processed by Webpack.
You need to put any JS and CSS files inside src, or Webpack won�t see them.

Only files inside public can be used from public/index.html.
Read instructions below for using assets from JavaScript and HTML.

You can, however, create more top-level directories.
They will not be included in the production build so you can use them for things like documentation.

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.

Supported Language Features and Polyfills

This project supports a superset of the latest JavaScript standard.
In addition to ES6 syntax features, it also supports:

• Exponentiation Operator (ES2016).
• Async/await (ES2017).
• Object Rest/Spread Properties (stage 3 proposal).
• Class Fields and Static Properties (stage 2 proposal).
• JSX and Flow syntax.

Learn more about different proposal stages.

While we recommend to use experimental proposals with some caution, Facebook heavily uses these features in the product code, so we intend to provide codemods if any of these proposals change in the future.

Note that the project only includes a few ES6 polyfills:

• Object.assign() via object-assign.
• Promise via promise.
• fetch() via whatwg-fetch.

If you use any other ES6+ features that need runtime support (such as Array.from() or Symbol), make sure you are including the appropriate polyfills manually, or that the browsers you are targeting already support them.

Syntax Highlighting in the Editor

To configure the syntax highlighting in your favorite text editor, head to the relevant Babel documentation page and follow the instructions. Some of the most popular editors are covered.

Displaying Lint Output in the Editor

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

Some editors, including Sublime Text, Atom, and Visual Studio Code, provide plugins for ESLint.

They are not required for linting. You should see the linter output right in your terminal as well as the browser console. However, if you prefer the lint results to appear right in your editor, there are some extra steps you can do.

You would need to install an ESLint plugin for your editor first.

A note for Atom linter-eslint users

If you are using the Atom linter-eslint plugin, make sure that Use global ESLint installation option is checked:

For Visual Studio Code users

VS Code ESLint plugin automatically detects Create React App's configuration file. So you do not need to create eslintrc.json at the root directory, except when you want to add your own rules. In that case, you should include CRA's config by adding this line:

{ // ... "extends": "react-app" }

Then add this block to the `package.json` file of your project:

```js
{
  // ...
  "eslintConfig": {
    "extends": "react-app"
  }
}

Finally, you will need to install some packages globally:

npm install -g eslint-config-react-app@0.3.0 eslint@3.8.1 babel-eslint@7.0.0 eslint-plugin-react@6.4.1 eslint-plugin-import@2.0.1 eslint-plugin-jsx-a11y@4.0.0 eslint-plugin-flowtype@2.21.0

We recognize that this is suboptimal, but it is currently required due to the way we hide the ESLint dependency. The ESLint team is already working on a solution to this so this may become unnecessary in a couple of months.

Debugging in the Editor

This feature is currently only supported by Visual Studio Code editor.

Visual Studio Code supports live-editing and debugging out of the box with Create React App. This enables you as a developer to write and debug your React code without leaving the editor, and most importantly it enables you to have a continuous development workflow, where context switching is minimal, as you don�t have to switch between tools.

You would need to have the latest version of VS Code and VS Code Chrome Debugger Extension installed.

Then add the block below to your launch.json file and put it inside the .vscode folder in your app�s root directory.

{
  "version": "0.2.0",
  "configurations": [{
    "name": "Chrome",
    "type": "chrome",
    "request": "launch",
    "url": "http://localhost:3000",
    "webRoot": "${workspaceRoot}/src",
    "userDataDir": "${workspaceRoot}/.vscode/chrome",
    "sourceMapPathOverrides": {
      "webpack:///src/*": "${webRoot}/*"
    }
  }]
}

Start your app by running npm start, and start debugging in VS Code by pressing F5 or by clicking the green debug icon. You can now write code, set breakpoints, make changes to the code, and debug your newly modified code�all from your editor.

Changing the Page <title>

You can find the source HTML file in the public folder of the generated project. You may edit the <title> tag in it to change the title from �React App� to anything else.

Note that normally you wouldn�t edit files in the public folder very often. For example, adding a stylesheet is done without touching the HTML.

If you need to dynamically update the page title based on the content, you can use the browser document.title API. For more complex scenarios when you want to change the title from React components, you can use React Helmet, a third party library.

If you use a custom server for your app in production and want to modify the title before it gets sent to the browser, you can follow advice in this section. Alternatively, you can pre-build each page as a static HTML file which then loads the JavaScript bundle, which is covered here.

Installing a Dependency

The generated project includes React and ReactDOM as dependencies. It also includes a set of scripts used by Create React App as a development dependency. You may install other dependencies (for example, React Router) with npm:

npm install --save <library-name>

Importing a Component

This project setup supports ES6 modules thanks to Babel.
While you can still use require() and module.exports, we encourage you to use import and export instead.

For example:

Button.js

import React, { Component } from 'react';

class Button extends Component {
  render() {
    // ...
  }
}

export default Button; // Don�t forget to use export default!