docs: setting up babel, fixes regeneratorRuntime not defined (jestjs#…

…7701)

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Chore & Maintenance
 
 - `[website]` Fix broken help link on homepage ([#7706](https://github.com/facebook/jest/pull/7706))
+- `[docs]` Changed Babel setup documentation to correctly compile `async/await` ([#7701](https://github.com/facebook/jest/pull/7701))
 
 ### Performance
 

docs/GettingStarted.md

@@ -81,31 +81,51 @@ jest --init
 
 ### Using Babel
 
-To use [Babel](http://babeljs.io/), install the `babel-jest` and `@babel/core` packages via `yarn`:
+To use [Babel](http://babeljs.io/), install required dependencies via `yarn`:
 
 ```bash
-yarn add --dev babel-jest @babel/core
+yarn add --dev babel-jest @babel/core @babel/preset-env
 ```
 
-Don't forget to add a [`babel.config.js`](https://babeljs.io/docs/en/config-files) file in your project's root folder. For example, if you are using ES2018 and [React](https://reactjs.org) with the [`@babel/preset-env`](https://babeljs.io/docs/en/babel-preset-env) and [`@babel/preset-react`](https://babeljs.io/docs/en/babel-preset-react) presets:
+Configure Babel to target your current version of Node by creating a `babel.config.js` file in the root of your project:
 
-```js
+```javascript
+// babel.config.js
 module.exports = {
-  presets: ['@babel/preset-env', '@babel/preset-react'],
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        targets: {
+          node: 'current',
+        },
+      },
+    ],
+  ],
 };
 ```
 
-You are now set up to use all ES2018 features and React-specific syntax.
+**The ideal configuration for Babel will depend on your project.** See [Babel's docs](https://babeljs.io/docs/en/) for more details.
+
+Jest will set `process.env.NODE_ENV` to `'test'` if it's not set to something else. You can use that in your configuration to conditionally setup only the compilation needed for Jest, e.g.
+
+```javascript
+// babel.config.js
+module.exports = api => {
+  const isTest = api.env('test');
+  // You can use isTest to determine what presets and plugins to use.
+
+  return ...
+};
+```
 
 > Note: `babel-jest` is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. To avoid this behavior, you can explicitly reset the `transform` configuration option:
 
-```json
-// package.json
-{
-  "jest": {
-    "transform": {}
-  }
-}
+```javascript
+// jest.config.js
+module.exports = {
+  transform: {},
+};
 ```
 
 #### Babel 6

website/versioned_docs/version-24.0/GettingStarted.md

@@ -82,31 +82,51 @@ jest --init
 
 ### Using Babel
 
-To use [Babel](http://babeljs.io/), install the `babel-jest` and `@babel/core` packages via `yarn`:
+To use [Babel](http://babeljs.io/), install required dependencies via `yarn`:
 
 ```bash
-yarn add --dev babel-jest @babel/core
+yarn add --dev babel-jest @babel/core @babel/preset-env
 ```
 
-Don't forget to add a [`babel.config.js`](https://babeljs.io/docs/en/config-files) file in your project's root folder. For example, if you are using ES2018 and [React](https://reactjs.org) with the [`@babel/preset-env`](https://babeljs.io/docs/en/babel-preset-env) and [`@babel/preset-react`](https://babeljs.io/docs/en/babel-preset-react) presets:
+Configure Babel to target your current version of Node by creating a `babel.config.js` file in the root of your project:
 
-```js
+```javascript
+// babel.config.js
 module.exports = {
-  presets: ['@babel/preset-env', '@babel/preset-react'],
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        targets: {
+          node: 'current',
+        },
+      },
+    ],
+  ],
 };
 ```
 
-You are now set up to use all ES2018 features and React-specific syntax.
+**The ideal configuration for Babel will depend on your project.** See [Babel's docs](https://babeljs.io/docs/en/) for more details.
+
+Jest will set `process.env.NODE_ENV` to `'test'` if it's not set to something else. You can use that in your configuration to conditionally setup only the compilation needed for Jest, e.g.
+
+```javascript
+// babel.config.js
+module.exports = api => {
+  const isTest = api.env('test');
+  // You can use isTest to determine what presets and plugins to use.
+
+  return ...
+};
+```
 
 > Note: `babel-jest` is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. To avoid this behavior, you can explicitly reset the `transform` configuration option:
 
-```json
-// package.json
-{
-  "jest": {
-    "transform": {}
-  }
-}
+```javascript
+// jest.config.js
+module.exports = {
+  transform: {},
+};
 ```
 
 #### Babel 6