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Joe Haddad
2018-09-26 10:36:30 -04:00
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@@ -110,8 +110,8 @@ You can find the most recent version of this guide [here](https://github.com/fac
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).
- `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`.
@@ -150,8 +150,8 @@ my-app/
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.
- `public/index.html` is the page template;
- `src/index.js` is the JavaScript entry point.
You can delete or rename the other files.
@@ -212,12 +212,12 @@ You can refer [to the React documentation](https://reactjs.org/docs/react-dom.ht
This project supports a superset of the latest JavaScript standard.<br>
In addition to [ES6](https://github.com/lukehoban/es6features) syntax features, it also supports:
* [Exponentiation Operator](https://github.com/rwaldron/exponentiation-operator) (ES2016).
* [Async/await](https://github.com/tc39/ecmascript-asyncawait) (ES2017).
* [Object Rest/Spread Properties](https://github.com/tc39/proposal-object-rest-spread) (ES2018).
* [Dynamic import()](https://github.com/tc39/proposal-dynamic-import) (stage 3 proposal)
* [Class Fields and Static Properties](https://github.com/tc39/proposal-class-public-fields) (part of stage 3 proposal).
* [JSX](https://facebook.github.io/react/docs/introducing-jsx.html) and [Flow](https://flow.org/) syntax.
- [Exponentiation Operator](https://github.com/rwaldron/exponentiation-operator) (ES2016).
- [Async/await](https://github.com/tc39/ecmascript-asyncawait) (ES2017).
- [Object Rest/Spread Properties](https://github.com/tc39/proposal-object-rest-spread) (ES2018).
- [Dynamic import()](https://github.com/tc39/proposal-dynamic-import) (stage 3 proposal)
- [Class Fields and Static Properties](https://github.com/tc39/proposal-class-public-fields) (part of stage 3 proposal).
- [JSX](https://facebook.github.io/react/docs/introducing-jsx.html) and [Flow](https://flow.org/) syntax.
Learn more about [different proposal stages](https://babeljs.io/docs/plugins/#presets-stage-x-experimental-presets-).
@@ -225,9 +225,9 @@ While we recommend using experimental proposals with some caution, Facebook heav
Note that **the project only includes a few ES6 [polyfills](https://en.wikipedia.org/wiki/Polyfill)**:
* [`Object.assign()`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign) via [`object-assign`](https://github.com/sindresorhus/object-assign).
* [`Promise`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) via [`promise`](https://github.com/then/promise).
* [`fetch()`](https://developer.mozilla.org/en/docs/Web/API/Fetch_API) via [`whatwg-fetch`](https://github.com/github/fetch).
- [`Object.assign()`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign) via [`object-assign`](https://github.com/sindresorhus/object-assign).
- [`Promise`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) via [`promise`](https://github.com/then/promise).
- [`fetch()`](https://developer.mozilla.org/en/docs/Web/API/Fetch_API) via [`whatwg-fetch`](https://github.com/github/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.
@@ -239,8 +239,8 @@ To configure the syntax highlighting in your favorite text editor, head to the [
## Displaying Lint Output in the Editor
>Note: this feature is available with `react-scripts@0.2.0` and higher.<br>
>It also only works with npm 3 or higher.
> Note: this feature is available with `react-scripts@0.2.0` and higher.<br>
> It also only works with npm 3 or higher.
Some editors, including Sublime Text, Atom, and Visual Studio Code, provide plugins for ESLint.
@@ -275,19 +275,22 @@ Then add the block below to your `launch.json` file and put it inside the `.vsco
```json
{
"version": "0.2.0",
"configurations": [{
"name": "Chrome",
"type": "chrome",
"request": "launch",
"url": "http://localhost:3000",
"webRoot": "${workspaceRoot}/src",
"sourceMapPathOverrides": {
"webpack:///src/*": "${webRoot}/*"
"configurations": [
{
"name": "Chrome",
"type": "chrome",
"request": "launch",
"url": "http://localhost:3000",
"webRoot": "${workspaceRoot}/src",
"sourceMapPathOverrides": {
"webpack:///src/*": "${webRoot}/*"
}
}
}]
]
}
```
>Note: the URL may be different if you've made adjustments via the [HOST or PORT environment variables](#advanced-configuration).
> Note: the URL may be different if you've made adjustments via the [HOST or PORT environment variables](#advanced-configuration).
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.
@@ -299,7 +302,7 @@ You would need to have [WebStorm](https://www.jetbrains.com/webstorm/) and [JetB
In the WebStorm menu `Run` select `Edit Configurations...`. Then click `+` and select `JavaScript Debug`. Paste `http://localhost:3000` into the URL field and save the configuration.
>Note: the URL may be different if you've made adjustments via the [HOST or PORT environment variables](#advanced-configuration).
> Note: the URL may be different if you've made adjustments via the [HOST or PORT environment variables](#advanced-configuration).
Start your app by running `npm start`, then press `^D` on macOS or `F9` on Windows and Linux or click the green debug icon to start debugging in WebStorm.
@@ -321,9 +324,9 @@ Alternatively you may use `yarn`:
yarn add husky lint-staged prettier
```
* `husky` makes it easy to use githooks as if they are npm scripts.
* `lint-staged` allows us to run scripts on staged files in git. See this [blog post about lint-staged to learn more about it](https://medium.com/@okonetchnikov/make-linting-great-again-f3890e1ad6b8).
* `prettier` is the JavaScript formatter we will run before commits.
- `husky` makes it easy to use githooks as if they are npm scripts.
- `lint-staged` allows us to run scripts on staged files in git. See this [blog post about lint-staged to learn more about it](https://medium.com/@okonetchnikov/make-linting-great-again-f3890e1ad6b8).
- `prettier` is the JavaScript formatter we will run before commits.
Now we can make sure every file is formatted correctly by adding a few lines to the `package.json` in the project root.
@@ -405,7 +408,6 @@ export default Button; // Don’t forget to use export default!
### `DangerButton.js`
```js
import React, { Component } from 'react';
import Button from './Button'; // Import a component from another file
@@ -427,9 +429,9 @@ Named exports are useful for utility modules that export several functions. A mo
Learn more about ES6 modules:
* [When to use the curly braces?](http://stackoverflow.com/questions/36795819/react-native-es-6-when-should-i-use-curly-braces-for-import/36796281#36796281)
* [Exploring ES6: Modules](http://exploringjs.com/es6/ch_modules.html)
* [Understanding ES6: Modules](https://leanpub.com/understandinges6/read#leanpub-auto-encapsulating-code-with-modules)
- [When to use the curly braces?](http://stackoverflow.com/questions/36795819/react-native-es-6-when-should-i-use-curly-braces-for-import/36796281#36796281)
- [Exploring ES6: Modules](http://exploringjs.com/es6/ch_modules.html)
- [Understanding ES6: Modules](https://leanpub.com/understandinges6/read#leanpub-auto-encapsulating-code-with-modules)
## Code Splitting
@@ -446,6 +448,7 @@ const moduleA = 'Hello';
export { moduleA };
```
### `App.js`
```js
@@ -545,7 +548,6 @@ import React, { Component } from 'react';
import styles from './Button.module.css'; // Import css modules stylesheet as styles
import './another-stylesheet.css'; // Import regular stylesheet
class Button extends Component {
render() {
// reference as a js object
@@ -553,7 +555,9 @@ class Button extends Component {
}
}
```
### `exported HTML`
No clashes from other `.error` class names
```html
@@ -586,11 +590,11 @@ becomes this:
display: flex;
-webkit-box-orient: horizontal;
-webkit-box-direction: normal;
-ms-flex-direction: row;
flex-direction: row;
-ms-flex-direction: row;
flex-direction: row;
-webkit-box-align: center;
-ms-flex-align: center;
align-items: center;
-ms-flex-align: center;
align-items: center;
}
```
@@ -625,13 +629,13 @@ Then in `package.json`, add the following lines to `scripts`:
"test": "react-scripts test",
```
>Note: To use a different preprocessor, replace `build-css` and `watch-css` commands according to your preprocessor’s documentation.
> Note: To use a different preprocessor, replace `build-css` and `watch-css` commands according to your preprocessor’s documentation.
Now you can rename `src/App.css` to `src/App.scss` and run `npm run watch-css`. The watcher will find every Sass file in `src` subdirectories, and create a corresponding CSS file next to it, in our case overwriting `src/App.css`. Since `src/App.js` still imports `src/App.css`, the styles become a part of your application. You can now edit `src/App.scss`, and `src/App.css` will be regenerated.
To share variables between Sass files, you can use Sass imports. For example, `src/App.scss` and other component style files could include `@import "./shared.scss";` with variable definitions.
To enable importing files without using relative paths, you can add the `--include-path` option to the command in `package.json`.
To enable importing files without using relative paths, you can add the `--include-path` option to the command in `package.json`.
```
"build-css": "node-sass-chokidar --include-path ./node_modules src/ -o src/",
@@ -682,13 +686,13 @@ Now running `npm start` and `npm run build` also builds Sass files.
`node-sass` has been reported as having the following issues:
- `node-sass --watch` has been reported to have *performance issues* in certain conditions when used in a virtual machine or with docker.
- `node-sass --watch` has been reported to have _performance issues_ in certain conditions when used in a virtual machine or with docker.
- Infinite styles compiling [#1939](https://github.com/facebook/create-react-app/issues/1939)
- `node-sass` has been reported as having issues with detecting new files in a directory [#1891](https://github.com/sass/node-sass/issues/1891)
`node-sass-chokidar` is used here as it addresses these issues.
`node-sass-chokidar` is used here as it addresses these issues.
## Adding Images, Fonts, and Files
@@ -733,7 +737,7 @@ An alternative way of handling static assets is described in the next section.
## Using the `public` Folder
>Note: this feature is available with `react-scripts@0.5.0` and higher.
> Note: this feature is available with `react-scripts@0.5.0` and higher.
### Changing the HTML
@@ -748,13 +752,13 @@ Note that we normally encourage you to `import` assets in JavaScript files inste
For example, see the sections on [adding a stylesheet](#adding-a-stylesheet) and [adding images and fonts](#adding-images-fonts-and-files).
This mechanism provides a number of benefits:
* Scripts and stylesheets get minified and bundled together to avoid extra network requests.
* Missing files cause compilation errors instead of 404 errors for your users.
* Result filenames include content hashes so you don’t need to worry about browsers caching their old versions.
- Scripts and stylesheets get minified and bundled together to avoid extra network requests.
- Missing files cause compilation errors instead of 404 errors for your users.
- Result filenames include content hashes so you don’t need to worry about browsers caching their old versions.
However there is an **escape hatch** that you can use to add an asset outside of the module system.
If you put a file into the `public` folder, it will **not** be processed by Webpack. Instead it will be copied into the build folder untouched. To reference assets in the `public` folder, you need to use a special variable called `PUBLIC_URL`.
If you put a file into the `public` folder, it will **not** be processed by Webpack. Instead it will be copied into the build folder untouched. To reference assets in the `public` folder, you need to use a special variable called `PUBLIC_URL`.
Inside `index.html`, you can use it like this:
@@ -779,19 +783,19 @@ render() {
Keep in mind the downsides of this approach:
* None of the files in `public` folder get post-processed or minified.
* Missing files will not be called at compilation time, and will cause 404 errors for your users.
* Result filenames won’t include content hashes so you’ll need to add query arguments or rename them every time they change.
- None of the files in `public` folder get post-processed or minified.
- Missing files will not be called at compilation time, and will cause 404 errors for your users.
- Result filenames won’t include content hashes so you’ll need to add query arguments or rename them every time they change.
### When to Use the `public` Folder
Normally we recommend importing [stylesheets](#adding-a-stylesheet), [images, and fonts](#adding-images-fonts-and-files) from JavaScript.
The `public` folder is useful as a workaround for a number of less common cases:
* You need a file with a specific name in the build output, such as [`manifest.webmanifest`](https://developer.mozilla.org/en-US/docs/Web/Manifest).
* You have thousands of images and need to dynamically reference their paths.
* You want to include a small script like [`pace.js`](http://github.hubspot.com/pace/docs/welcome/) outside of the bundled code.
* Some library may be incompatible with Webpack and you have no other option but to include it as a `<script>` tag.
- You need a file with a specific name in the build output, such as [`manifest.webmanifest`](https://developer.mozilla.org/en-US/docs/Web/Manifest).
- You have thousands of images and need to dynamically reference their paths.
- You want to include a small script like [`pace.js`](http://github.hubspot.com/pace/docs/welcome/) outside of the bundled code.
- Some library may be incompatible with Webpack and you have no other option but to include it as a `<script>` tag.
Note that if you add a `<script>` that declares global variables, you also need to read the next section on using them.
@@ -825,7 +829,7 @@ Alternatively you may use `yarn`:
yarn add bootstrap@4 reactstrap
```
Import Bootstrap CSS and optionally Bootstrap theme CSS in the beginning of your ```src/index.js``` file:
Import Bootstrap CSS and optionally Bootstrap theme CSS in the beginning of your `src/index.js` file:
```js
import 'bootstrap/dist/css/bootstrap.css';
@@ -833,7 +837,7 @@ import 'bootstrap/dist/css/bootstrap.css';
// components takes precedence over default styles.
```
Import required reactstrap components within ```src/App.js``` file or your custom component files:
Import required reactstrap components within `src/App.js` file or your custom component files:
```js
import { Button } from 'reactstrap';
@@ -846,9 +850,9 @@ Now you are ready to use the imported reactstrap components within your componen
Sometimes you might need to tweak the visual styles of Bootstrap (or equivalent package).<br>
We suggest the following approach:
* Create a new package that depends on the package you wish to customize, e.g. Bootstrap.
* Add the necessary build steps to tweak the theme, and publish your package on npm.
* Install your own theme npm package as a dependency of your app.
- Create a new package that depends on the package you wish to customize, e.g. Bootstrap.
- Add the necessary build steps to tweak the theme, and publish your package on npm.
- Install your own theme npm package as a dependency of your app.
Here is an example of adding a [customized Bootstrap](https://medium.com/@tacomanator/customizing-create-react-app-aa9ffb88165) that follows these steps.
@@ -893,7 +897,7 @@ Note that [you may need to configure your production server to support client-si
## Adding Custom Environment Variables
>Note: this feature is available with `react-scripts@0.2.3` and higher.
> Note: this feature is available with `react-scripts@0.2.3` and higher.
Your project can consume variables declared in your environment as if they were declared locally in your JS files. By
default you will have `NODE_ENV` defined for you, and any other environment variables starting with
@@ -901,7 +905,7 @@ default you will have `NODE_ENV` defined for you, and any other environment vari
**The environment variables are embedded during the build time**. Since Create React App produces a static HTML/CSS/JS bundle, it can’t possibly read them at runtime. To read them at runtime, you would need to load HTML into memory on the server and replace placeholders in runtime, just like [described here](#injecting-data-from-the-server-into-the-page). Alternatively you can rebuild the app on the server anytime you change them.
>Note: You must create custom environment variables beginning with `REACT_APP_`. Any other variables except `NODE_ENV` will be ignored to avoid accidentally [exposing a private key on the machine that could have the same name](https://github.com/facebook/create-react-app/issues/865#issuecomment-252199527). Changing any environment variables will require you to restart the development server if it is running.
> Note: You must create custom environment variables beginning with `REACT_APP_`. Any other variables except `NODE_ENV` will be ignored to avoid accidentally [exposing a private key on the machine that could have the same name](https://github.com/facebook/create-react-app/issues/865#issuecomment-252199527). Changing any environment variables will require you to restart the development server if it is running.
These environment variables will be defined for you on `process.env`. For example, having an environment
variable named `REACT_APP_SECRET_CODE` will be exposed in your JS as `process.env.REACT_APP_SECRET_CODE`.
@@ -956,7 +960,7 @@ When you compile the app with `npm run build`, the minification step will strip
### Referencing Environment Variables in the HTML
>Note: this feature is available with `react-scripts@0.9.0` and higher.
> Note: this feature is available with `react-scripts@0.9.0` and higher.
You can also access the environment variables starting with `REACT_APP_` in the `public/index.html`. For example:
@@ -966,8 +970,8 @@ You can also access the environment variables starting with `REACT_APP_` in the
Note that the caveats from the above section apply:
* Apart from a few built-in variables (`NODE_ENV` and `PUBLIC_URL`), variable names must start with `REACT_APP_` to work.
* The environment variables are injected at build time. If you need to inject them at runtime, [follow this approach instead](#generating-dynamic-meta-tags-on-the-server).
- Apart from a few built-in variables (`NODE_ENV` and `PUBLIC_URL`), variable names must start with `REACT_APP_` to work.
- The environment variables are injected at build time. If you need to inject them at runtime, [follow this approach instead](#generating-dynamic-meta-tags-on-the-server).
### Adding Temporary Environment Variables In Your Shell
@@ -996,41 +1000,42 @@ REACT_APP_SECRET_CODE=abcdef npm start
### Adding Development Environment Variables In `.env`
>Note: this feature is available with `react-scripts@0.5.0` and higher.
> Note: this feature is available with `react-scripts@0.5.0` and higher.
To define permanent environment variables, create a file called `.env` in the root of your project:
```
REACT_APP_SECRET_CODE=abcdef
```
>Note: You must create custom environment variables beginning with `REACT_APP_`. Any other variables except `NODE_ENV` will be ignored to avoid [accidentally exposing a private key on the machine that could have the same name](https://github.com/facebook/create-react-app/issues/865#issuecomment-252199527). Changing any environment variables will require you to restart the development server if it is running.
> Note: You must create custom environment variables beginning with `REACT_APP_`. Any other variables except `NODE_ENV` will be ignored to avoid [accidentally exposing a private key on the machine that could have the same name](https://github.com/facebook/create-react-app/issues/865#issuecomment-252199527). Changing any environment variables will require you to restart the development server if it is running.
`.env` files **should be** checked into source control (with the exclusion of `.env*.local`).
#### What other `.env` files can be used?
>Note: this feature is **available with `react-scripts@1.0.0` and higher**.
> Note: this feature is **available with `react-scripts@1.0.0` and higher**.
* `.env`: Default.
* `.env.local`: Local overrides. **This file is loaded for all environments except test.**
* `.env.development`, `.env.test`, `.env.production`: Environment-specific settings.
* `.env.development.local`, `.env.test.local`, `.env.production.local`: Local overrides of environment-specific settings.
- `.env`: Default.
- `.env.local`: Local overrides. **This file is loaded for all environments except test.**
- `.env.development`, `.env.test`, `.env.production`: Environment-specific settings.
- `.env.development.local`, `.env.test.local`, `.env.production.local`: Local overrides of environment-specific settings.
Files on the left have more priority than files on the right:
* `npm start`: `.env.development.local`, `.env.development`, `.env.local`, `.env`
* `npm run build`: `.env.production.local`, `.env.production`, `.env.local`, `.env`
* `npm test`: `.env.test.local`, `.env.test`, `.env` (note `.env.local` is missing)
- `npm start`: `.env.development.local`, `.env.development`, `.env.local`, `.env`
- `npm run build`: `.env.production.local`, `.env.production`, `.env.local`, `.env`
- `npm test`: `.env.test.local`, `.env.test`, `.env` (note `.env.local` is missing)
These variables will act as the defaults if the machine does not explicitly set them.<br>
Please refer to the [dotenv documentation](https://github.com/motdotla/dotenv) for more details.
>Note: If you are defining environment variables for development, your CI and/or hosting platform will most likely need
these defined as well. Consult their documentation how to do this. For example, see the documentation for [Travis CI](https://docs.travis-ci.com/user/environment-variables/) or [Heroku](https://devcenter.heroku.com/articles/config-vars).
> Note: If you are defining environment variables for development, your CI and/or hosting platform will most likely need
> these defined as well. Consult their documentation how to do this. For example, see the documentation for [Travis CI](https://docs.travis-ci.com/user/environment-variables/) or [Heroku](https://devcenter.heroku.com/articles/config-vars).
#### Expanding Environment Variables In `.env`
>Note: this feature is available with `react-scripts@1.1.0` and higher.
> Note: this feature is available with `react-scripts@1.1.0` and higher.
Expand variables already on your machine for use in your `.env` file (using [dotenv-expand](https://github.com/motdotla/dotenv-expand)).
@@ -1055,15 +1060,15 @@ REACT_APP_BAR=$DOMAIN/bar
Many popular libraries use [decorators](https://medium.com/google-developers/exploring-es7-decorators-76ecb65fb841) in their documentation.<br>
Create React App doesn’t support decorator syntax at the moment because:
* It is an experimental proposal and is subject to change.
* The current specification version is not officially supported by Babel.
* If the specification changes, we won’t be able to write a codemod because we don’t use them internally at Facebook.
- It is an experimental proposal and is subject to change.
- The current specification version is not officially supported by Babel.
- If the specification changes, we won’t be able to write a codemod because we don’t use them internally at Facebook.
However in many cases you can rewrite decorator-based code without decorators just as fine.<br>
Please refer to these two threads for reference:
* [#214](https://github.com/facebook/create-react-app/issues/214)
* [#411](https://github.com/facebook/create-react-app/issues/411)
- [#214](https://github.com/facebook/create-react-app/issues/214)
- [#411](https://github.com/facebook/create-react-app/issues/411)
Create React App will add decorator support when the specification advances to a stable stage.
@@ -1101,7 +1106,7 @@ Check out [this tutorial](https://api-platform.com/docs/distribution).
## Proxying API Requests in Development
>Note: this feature is available with `react-scripts@0.2.3` and higher.
> Note: this feature is available with `react-scripts@0.2.3` and higher.
People often serve the front-end React app from the same host and port as their backend implementation.<br>
For example, a production setup might look like this after the app is deployed:
@@ -1133,9 +1138,9 @@ Keep in mind that `proxy` only has effect in development (with `npm start`), and
The `proxy` option supports HTTP, HTTPS and WebSocket connections.<br>
If the `proxy` option is **not** flexible enough for you, alternatively you can:
* [Configure the proxy yourself](#configuring-the-proxy-manually)
* Enable CORS on your server ([here’s how to do it for Express](http://enable-cors.org/server_expressjs.html)).
* Use [environment variables](#adding-custom-environment-variables) to inject the right server host and port into your app.
- [Configure the proxy yourself](#configuring-the-proxy-manually)
- Enable CORS on your server ([here’s how to do it for Express](http://enable-cors.org/server_expressjs.html)).
- Use [environment variables](#adding-custom-environment-variables) to inject the right server host and port into your app.
### "Invalid Host Header" Errors After Configuring Proxy
@@ -1143,7 +1148,7 @@ When you enable the `proxy` option, you opt into a more strict set of host check
This shouldn’t affect you when developing on `localhost`, but if you develop remotely like [described here](https://github.com/facebook/create-react-app/issues/2271), you will see this error in the browser after enabling the `proxy` option:
>Invalid Host header
> Invalid Host header
To work around it, you can specify your public development host in a file called `.env.development` in the root of your project:
@@ -1165,10 +1170,11 @@ We don’t recommend this approach.
### Configuring the Proxy Manually
>Note: this feature is available with `react-scripts@1.0.0` and higher.
> Note: this feature is available with `react-scripts@1.0.0` and higher.
If the `proxy` option is **not** flexible enough for you, you can specify an object in the following form (in `package.json`).<br>
You may also specify any configuration value [`http-proxy-middleware`](https://github.com/chimurai/http-proxy-middleware#options) or [`http-proxy`](https://github.com/nodejitsu/node-http-proxy#options) supports.
```js
{
// ...
@@ -1187,6 +1193,7 @@ All requests matching this path will be proxies, no exceptions. This includes re
If you need to specify multiple proxies, you may do so by specifying additional entries.
Matches are regular expressions, so that you can use a regexp to match multiple paths.
```js
{
// ...
@@ -1253,7 +1260,7 @@ Either way, you can proxy WebSocket requests manually in `package.json`:
## Using HTTPS in Development
>Note: this feature is available with `react-scripts@0.4.0` and higher.
> Note: this feature is available with `react-scripts@0.4.0` and higher.
You may require the dev server to serve pages over HTTPS. One particular case where this could be useful is when using [the "proxy" feature](#proxying-api-requests-in-development) to proxy requests to an API server when that API server is itself serving HTTPS.
@@ -1324,8 +1331,7 @@ Then, on the server, you can replace `__SERVER_DATA__` with a JSON of real data
## Running Tests
>Note: this feature is available with `react-scripts@0.3.0` and higher.<br>
>[Read the migration guide to learn how to enable it in older projects!](https://github.com/facebook/create-react-app/blob/master/CHANGELOG.md#migrating-from-023-to-030)
> Note: this feature is available with `react-scripts@0.3.0` and higher.<br> >[Read the migration guide to learn how to enable it in older projects!](https://github.com/facebook/create-react-app/blob/master/CHANGELOG.md#migrating-from-023-to-030)
Create React App uses [Jest](https://facebook.github.io/jest/) as its test runner. To prepare for this integration, we did a [major revamp](https://facebook.github.io/jest/blog/2016/09/01/jest-15.html) of Jest so if you heard bad things about it years ago, give it another try.
@@ -1339,9 +1345,9 @@ We recommend that you use a separate tool for browser end-to-end tests if you ne
Jest will look for test files with any of the following popular naming conventions:
* Files with `.js` suffix in `__tests__` folders.
* Files with `.test.js` suffix.
* Files with `.spec.js` suffix.
- Files with `.js` suffix in `__tests__` folders.
- Files with `.test.js` suffix.
- Files with `.spec.js` suffix.
The `.test.js` / `.spec.js` files (or the `__tests__` folders) can be located at any depth under the `src` top level folder.
@@ -1419,6 +1425,7 @@ As of Enzyme 3, you will need to install Enzyme along with an Adapter correspond
The adapter will also need to be configured in your [global setup file](#initializing-test-environment):
#### `src/setupTests.js`
```js
import { configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
@@ -1426,7 +1433,7 @@ 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](#initializing-test-environment) to learn how to add this after ejecting.
> 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](#initializing-test-environment) to learn how to add this after ejecting.
Now you can write a smoke test with it:
@@ -1465,7 +1472,7 @@ Nevertheless you can use a third-party assertion library like [Chai](http://chai
Additionally, you might find [jest-enzyme](https://github.com/blainekasten/enzyme-matchers) helpful to simplify your tests with readable matchers. The above `contains` code can be written more simply with jest-enzyme.
```js
expect(wrapper).toContainReact(welcome)
expect(wrapper).toContainReact(welcome);
```
To enable this, install `jest-enzyme`:
@@ -1501,30 +1508,31 @@ 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.
> 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`
```js
const localStorageMock = {
getItem: jest.fn(),
setItem: jest.fn(),
clear: jest.fn()
clear: jest.fn(),
};
global.localStorage = localStorageMock
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:
> 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:
>```js
>"jest": {
> ```js
> "jest": {
> // ...
> "setupTestFrameworkScriptFile": "<rootDir>/src/setupTests.js"
> }
> ```
> ```
### Focusing and Excluding Tests
@@ -1545,10 +1553,11 @@ Note that tests run much slower with coverage so it is recommended to run it sep
The default Jest coverage configuration can be overridden by adding any of the following supported keys to a Jest config in your package.json.
Supported overrides:
- [`collectCoverageFrom`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoveragefrom-array)
- [`coverageReporters`](https://facebook.github.io/jest/docs/en/configuration.html#coveragereporters-array-string)
- [`coverageThreshold`](https://facebook.github.io/jest/docs/en/configuration.html#coveragethreshold-object)
- [`snapshotSerializers`](https://facebook.github.io/jest/docs/en/configuration.html#snapshotserializers-array-string)
- [`collectCoverageFrom`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoveragefrom-array)
- [`coverageReporters`](https://facebook.github.io/jest/docs/en/configuration.html#coveragereporters-array-string)
- [`coverageThreshold`](https://facebook.github.io/jest/docs/en/configuration.html#coveragethreshold-object)
- [`snapshotSerializers`](https://facebook.github.io/jest/docs/en/configuration.html#snapshotserializers-array-string)
Example package.json:
@@ -1556,7 +1565,7 @@ Example package.json:
{
"name": "your-package",
"jest": {
"collectCoverageFrom" : [
"collectCoverageFrom": [
"src/**/*.{js,jsx}",
"!<rootDir>/node_modules/",
"!<rootDir>/path/to/dir/"
@@ -1584,10 +1593,12 @@ When creating a build of your application with `npm run build` linter warnings a
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](https://docs.travis-ci.com/user/getting-started/) guide for syncing your GitHub repository with Travis. You may need to initialize some settings manually in your [profile](https://travis-ci.org/profile) page.
1. Following the [Travis Getting started](https://docs.travis-ci.com/user/getting-started/) guide for syncing your GitHub repository with Travis. You may need to initialize some settings manually in your [profile](https://travis-ci.org/profile) page.
1. Add a `.travis.yml` file to your git repository.
```
language: node_js
node_js:
@@ -1599,6 +1610,7 @@ script:
- npm run build
- npm test
```
1. Trigger your first build with a git push.
1. [Customize your Travis CI Build](https://docs.travis-ci.com/user/customizing-the-build/) if needed.
@@ -1607,6 +1619,7 @@ script:
Follow [this article](https://medium.com/@knowbody/circleci-and-zeits-now-sh-c9b7eebcd3c1) to set up CircleCI with a Create React App project.
### On your own environment
##### Windows (cmd.exe)
```cmd
@@ -1641,7 +1654,7 @@ 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](https://github.com/facebook/create-react-app/issues/new) 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.
> If you find yourself doing this often in development, please [file an issue](https://github.com/facebook/create-react-app/issues/new) 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.
@@ -1659,15 +1672,15 @@ If you know that none of your tests depend on [jsdom](https://github.com/tmpvar/
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()`](https://facebook.github.io/react/docs/top-level-api.html#reactdom.render)
* [`TestUtils.renderIntoDocument()`](https://facebook.github.io/react/docs/test-utils.html#renderintodocument) ([a shortcut](https://github.com/facebook/react/blob/34761cf9a252964abfaab6faf74d473ad95d1f21/src/test/ReactTestUtils.js#L83-L91) for the above)
* [`mount()`](http://airbnb.io/enzyme/docs/api/mount.html) in [Enzyme](http://airbnb.io/enzyme/index.html)
- Any browser globals like `window` and `document`
- [`ReactDOM.render()`](https://facebook.github.io/react/docs/top-level-api.html#reactdom.render)
- [`TestUtils.renderIntoDocument()`](https://facebook.github.io/react/docs/test-utils.html#renderintodocument) ([a shortcut](https://github.com/facebook/react/blob/34761cf9a252964abfaab6faf74d473ad95d1f21/src/test/ReactTestUtils.js#L83-L91) for the above)
- [`mount()`](http://airbnb.io/enzyme/docs/api/mount.html) in [Enzyme](http://airbnb.io/enzyme/index.html)
In contrast, **jsdom is not needed** for the following APIs:
* [`TestUtils.createRenderer()`](https://facebook.github.io/react/docs/test-utils.html#shallow-rendering) (shallow rendering)
* [`shallow()`](http://airbnb.io/enzyme/docs/api/shallow.html) in [Enzyme](http://airbnb.io/enzyme/index.html)
- [`TestUtils.createRenderer()`](https://facebook.github.io/react/docs/test-utils.html#shallow-rendering) (shallow rendering)
- [`shallow()`](http://airbnb.io/enzyme/docs/api/shallow.html) in [Enzyme](http://airbnb.io/enzyme/index.html)
Finally, jsdom is also not needed for [snapshot testing](http://facebook.github.io/jest/blog/2016/07/27/jest-14.html).
@@ -1685,17 +1698,20 @@ If you use [Visual Studio Code](https://code.visualstudio.com), there is a [Jest
There are various ways to setup a debugger for your Jest tests. We cover debugging in Chrome and [Visual Studio Code](https://code.visualstudio.com/).
>Note: debugging tests requires Node 8 or higher.
> 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`
```json
"scripts": {
"test:debug": "react-scripts --inspect-brk test --runInBand"
}
```
Place `debugger;` statements in any test and run:
```bash
$ npm run test:debug
```
@@ -1703,19 +1719,21 @@ $ 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.
> 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](https://code.visualstudio.com).
Use the following [`launch.json`](https://code.visualstudio.com/docs/editor/debugging#_launch-configurations) configuration file:
```
{
"version": "0.2.0",
@@ -1744,9 +1762,9 @@ Use the following [`launch.json`](https://code.visualstudio.com/docs/editor/debu
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.
- 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.
@@ -1776,10 +1794,10 @@ After that, follow the instructions on the screen.
Learn more about React Storybook:
* [Learn Storybook (tutorial)](https://learnstorybook.com)
* [Documentation](https://storybook.js.org/basics/introduction/)
* [GitHub Repo](https://github.com/storybooks/storybook)
* [Snapshot Testing UI](https://github.com/storybooks/storybook/tree/master/addons/storyshots) with Storybook + addon/storyshot
- [Learn Storybook (tutorial)](https://learnstorybook.com)
- [Documentation](https://storybook.js.org/basics/introduction/)
- [GitHub Repo](https://github.com/storybooks/storybook)
- [Snapshot Testing UI](https://github.com/storybooks/storybook/tree/master/addons/storyshots) with Storybook + addon/storyshot
### Getting Started with Styleguidist
@@ -1816,8 +1834,8 @@ After that, follow the instructions on the screen.
Learn more about React Styleguidist:
* [GitHub Repo](https://github.com/styleguidist/react-styleguidist)
* [Documentation](https://react-styleguidist.js.org/docs/getting-started.html)
- [GitHub Repo](https://github.com/styleguidist/react-styleguidist)
- [Documentation](https://react-styleguidist.js.org/docs/getting-started.html)
## Publishing Components to npm
@@ -1848,9 +1866,9 @@ As the comment states, switching `serviceWorker.unregister()` to
Offline-first 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.
- 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`](https://github.com/goldhand/sw-precache-webpack-plugin)
is integrated into production configuration,
@@ -1868,59 +1886,59 @@ If you do decide to opt-in to service worker registration, please take the
following into account:
1. Service workers [require HTTPS](https://developers.google.com/web/fundamentals/getting-started/primers/service-workers#you_need_https),
although to facilitate local testing, that policy
[does not apply to `localhost`](http://stackoverflow.com/questions/34160509/options-for-testing-service-workers-via-http/34161385#34161385).
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.
although to facilitate local testing, that policy
[does not apply to `localhost`](http://stackoverflow.com/questions/34160509/options-for-testing-service-workers-via-http/34161385#34161385).
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.
1. Service workers are [not supported](https://jakearchibald.github.io/isserviceworkerready/#moar)
in older web browsers. Service worker registration [won't be attempted](src/registerServiceWorker.js)
on browsers that lack support.
in older web browsers. Service worker registration [won't be attempted](src/registerServiceWorker.js)
on browsers that lack support.
1. The service worker is only enabled in the [production environment](#deployment),
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.
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.
1. 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](#deployment) have
instructions for using other methods. *Be sure to always use an
incognito window to avoid complications with your browser cache.*
1. 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](#deployment) have
instructions for using other methods. _Be sure to always use an
incognito window to avoid complications with your browser cache._
1. If possible, configure your production environment to serve the generated
`service-worker.js` [with HTTP caching disabled](http://stackoverflow.com/questions/38843970/service-worker-javascript-update-frequency-every-24-hours).
If that's not possible—[GitHub Pages](#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.
`service-worker.js` [with HTTP caching disabled](http://stackoverflow.com/questions/38843970/service-worker-javascript-update-frequency-every-24-hours).
If that's not possible—[GitHub Pages](#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.
1. Users aren't always familiar with offline-first web apps. It can be useful to
[let the user know](https://developers.google.com/web/fundamentals/instant-and-offline/offline-ux#inform_the_user_when_the_app_is_ready_for_offline_consumption)
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`](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.
[let the user know](https://developers.google.com/web/fundamentals/instant-and-offline/offline-ux#inform_the_user_when_the_app_is_ready_for_offline_consumption)
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`](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.
1. By default, the generated service worker file will not intercept or cache any
cross-origin traffic, like HTTP [API requests](#integrating-with-an-api-backend),
images, or embeds loaded from a different domain. If you would like to use a
runtime caching strategy for those requests, you can [`eject`](#npm-run-eject)
and then configure the
[`runtimeCaching`](https://github.com/GoogleChrome/sw-precache#runtimecaching-arrayobject)
option in the `SWPrecacheWebpackPlugin` section of
[`webpack.config.prod.js`](../config/webpack.config.prod.js).
cross-origin traffic, like HTTP [API requests](#integrating-with-an-api-backend),
images, or embeds loaded from a different domain. If you would like to use a
runtime caching strategy for those requests, you can [`eject`](#npm-run-eject)
and then configure the
[`runtimeCaching`](https://github.com/GoogleChrome/sw-precache#runtimecaching-arrayobject)
option in the `SWPrecacheWebpackPlugin` section of
[`webpack.config.prod.js`](../config/webpack.config.prod.js).
### Progressive Web App Metadata
@@ -2010,7 +2028,7 @@ const app = express();
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'));
});
@@ -2083,6 +2101,7 @@ This will let Create React App correctly infer the root path to use in the gener
More information [here](https://reacttraining.com/react-router/web/api/BrowserRouter/basename-string).<br>
<br>
For example:
```js
<BrowserRouter basename="/calendar"/>
<Link to="/today"/> // renders <a href="/calendar/today">
@@ -2090,7 +2109,7 @@ For example:
#### Serving the Same Build from Different Paths
>Note: this feature is available with `react-scripts@0.9.0` and higher.
> 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`:
@@ -2109,19 +2128,19 @@ For example, to create a build environment for a staging environment:
1. Create a file called `.env.staging`
1. Set environment variables as you would any other `.env` file (e.g. `REACT_APP_API_URL=http://api-staging.example.com`)
1. Install [env-cmd](https://www.npmjs.com/package/env-cmd)
```sh
$ npm install env-cmd --save
$ # or
$ yarn add env-cmd
```
```sh
$ npm install env-cmd --save
$ # or
$ yarn add env-cmd
```
1. Add a new script to your `package.json`, building with your new environment:
```json
{
"scripts": {
"build:staging": "env-cmd .env.staging npm run build",
}
}
```
```json
{
"scripts": {
"build:staging": "env-cmd .env.staging npm run build"
}
}
```
Now you can run `npm run build:staging` to build with the staging environment config.
You can specify other environments in the same way.
@@ -2209,7 +2228,7 @@ For more information see [Add Firebase to your JavaScript Project](https://fireb
### [GitHub Pages](https://pages.github.com/)
>Note: this feature is available with `react-scripts@0.2.0` and higher.
> Note: this feature is available with `react-scripts@0.2.0` and higher.
#### Step 1: Add `homepage` to `package.json`
@@ -2229,6 +2248,7 @@ or for a GitHub user page:
```
or for a custom domain page:
```json
"homepage": "https://mywebsite.com",
```
@@ -2268,6 +2288,7 @@ additional modifications:
1. First, change your repository's source branch to be any branch other than **master**.
1. Additionally, tweak your `package.json` scripts to push deployments to **master**:
```diff
"scripts": {
"predeploy": "npm run build",
@@ -2303,8 +2324,8 @@ mywebsite.com
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](https://reacttraining.com/react-router/web/api/Router) 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](https://github.com/rafrex/spa-github-pages).
- 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](https://reacttraining.com/react-router/web/api/Router) 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](https://github.com/rafrex/spa-github-pages).
#### Troubleshooting
@@ -2395,11 +2416,11 @@ Now offers a zero-configuration single-command deployment. You can use `now` to
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)
```
```
> 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.
Paste that URL into your browser when the build is complete, and you will see your deployed app.
Details are available in [this article.](https://zeit.co/blog/unlimited-static)
@@ -2423,18 +2444,18 @@ Note that in order to support routers that use HTML5 `pushState` API, you may wa
You can adjust various development and production settings by setting environment variables in your shell or with [.env](#adding-development-environment-variables-in-env).
Variable | Development | Production | Usage
:--- | :---: | :---: | :---
BROWSER | :white_check_mark: | :x: | By default, Create React App will open the default system browser, favoring Chrome on macOS. Specify a [browser](https://github.com/sindresorhus/opn#app) 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 | :white_check_mark: | :x: | By default, the development web server binds to `localhost`. You may use this variable to specify a different host.
PORT | :white_check_mark: | :x: | 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 | :white_check_mark: | :x: | When set to `true`, Create React App will run the development server in `https` mode.
PUBLIC_URL | :x: | :white_check_mark: | Create React App assumes your application is hosted at the serving web server's root or a subpath as specified in [`package.json` (`homepage`)](#building-for-relative-paths). 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 | :large_orange_diamond: | :white_check_mark: | 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 | :white_check_mark: | :x: | 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](https://github.com/facebook/create-react-app/issues/2636). Setting this environment variable overrides the automatic detection. If you do it, make sure your systems [PATH](https://en.wikipedia.org/wiki/PATH_(variable)) environment variable points to your editor’s bin folder. You can also set it to `none` to disable it completely.
CHOKIDAR_USEPOLLING | :white_check_mark: | :x: | 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 | :x: | :white_check_mark: | When set to `false`, source maps are not generated for a production build. This solves OOM issues on some smaller machines.
NODE_PATH | :white_check_mark: | :white_check_mark: | Same as [`NODE_PATH` in Node.js](https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders), but only relative folders are allowed. Can be handy for emulating a monorepo setup by setting `NODE_PATH=src`.
| Variable | Development | Production | Usage |
| :------------------ | :--------------------: | :----------------: | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BROWSER | :white_check_mark: | :x: | By default, Create React App will open the default system browser, favoring Chrome on macOS. Specify a [browser](https://github.com/sindresorhus/opn#app) 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 | :white_check_mark: | :x: | By default, the development web server binds to `localhost`. You may use this variable to specify a different host. |
| PORT | :white_check_mark: | :x: | 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 | :white_check_mark: | :x: | When set to `true`, Create React App will run the development server in `https` mode. |
| PUBLIC_URL | :x: | :white_check_mark: | Create React App assumes your application is hosted at the serving web server's root or a subpath as specified in [`package.json` (`homepage`)](#building-for-relative-paths). 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 | :large_orange_diamond: | :white_check_mark: | 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 | :white_check_mark: | :x: | 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](https://github.com/facebook/create-react-app/issues/2636). Setting this environment variable overrides the automatic detection. If you do it, make sure your systems [PATH](<https://en.wikipedia.org/wiki/PATH_(variable)>) environment variable points to your editor’s bin folder. You can also set it to `none` to disable it completely. |
| CHOKIDAR_USEPOLLING | :white_check_mark: | :x: | 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 | :x: | :white_check_mark: | When set to `false`, source maps are not generated for a production build. This solves OOM issues on some smaller machines. |
| NODE_PATH | :white_check_mark: | :white_check_mark: | Same as [`NODE_PATH` in Node.js](https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders), but only relative folders are allowed. Can be handy for emulating a monorepo setup by setting `NODE_PATH=src`. |
## Troubleshooting
@@ -2443,12 +2464,12 @@ NODE_PATH | :white_check_mark: | :white_check_mark: | Same as [`NODE_PATH` in N
When you save a file while `npm start` is running, the browser should refresh with the updated code.<br>
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](https://github.com/facebook/create-react-app/issues/1164) 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”](https://webpack.js.org/guides/development/#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](https://github.com/webpack/watchpack/issues/42).
* On Linux and macOS, you might need to [tweak system settings](https://github.com/webpack/docs/wiki/troubleshooting#not-enough-watchers) 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 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](https://github.com/facebook/create-react-app/issues/1164) 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”](https://webpack.js.org/guides/development/#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](https://github.com/webpack/watchpack/issues/42).
- On Linux and macOS, you might need to [tweak system settings](https://github.com/webpack/docs/wiki/troubleshooting#not-enough-watchers) 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](https://github.com/facebook/create-react-app/issues/659).
@@ -2458,9 +2479,9 @@ If you run `npm test` and the console gets stuck after printing `react-scripts t
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](https://github.com/facebook/jest/issues/1767)
* [facebook/watchman#358](https://github.com/facebook/watchman/issues/358)
* [ember-cli/ember-cli#6259](https://github.com/ember-cli/ember-cli/issues/6259)
- [facebook/jest#1767](https://github.com/facebook/jest/issues/1767)
- [facebook/watchman#358](https://github.com/facebook/watchman/issues/358)
- [ember-cli/ember-cli#6259](https://github.com/ember-cli/ember-cli/issues/6259)
It is reported that installing Watchman 4.7.0 or newer fixes the issue. If you use [Homebrew](http://brew.sh/), you can run these commands to update it:
@@ -2474,13 +2495,13 @@ You can find [other installation methods](https://facebook.github.io/watchman/do
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.
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.
> 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](https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04) to the machine you’re building on, or build the project locally.
@@ -2523,7 +2544,8 @@ Some third-party packages don't compile their code to ES5 before publishing to n
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**.
- 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.
@@ -2533,7 +2555,7 @@ In the future, we might start automatically compiling incompatible third-party m
## Alternatives to Ejecting
[Ejecting](#npm-run-eject) 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](https://auth0.com/blog/how-to-configure-create-react-app/) dives into how to do it in depth. You can find more discussion in [this issue](https://github.com/facebook/create-react-app/issues/682).
[Ejecting](#npm-run-eject) 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](https://auth0.com/blog/how-to-configure-create-react-app/) dives into how to do it in depth. You can find more discussion in [this issue](https://github.com/facebook/create-react-app/issues/682).
## Something Missing?