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# babel-plugin-transform-es2015-modules-commonjs
> This plugin transforms ES2015 modules to [CommonJS](http://wiki.commonjs.org/wiki/Modules/1.1).
## Example
**In**
```javascript
export default 42;
```
**Out**
```javascript
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = 42;
```
## Installation
```sh
npm install --save-dev babel-plugin-transform-es2015-modules-commonjs
```
## Usage
### Via `.babelrc` (Recommended)
**.babelrc**
```js
// without options
{
"plugins": ["transform-es2015-modules-commonjs"]
}
// with options
{
"plugins": [
["transform-es2015-modules-commonjs", {
"allowTopLevelThis": true
}]
]
}
```
### Via CLI
```sh
babel --plugins transform-es2015-modules-commonjs script.js
```
### Via Node API
```javascript
require("babel-core").transform("code", {
plugins: ["transform-es2015-modules-commonjs"]
});
```
## Options
### `loose`
`boolean`, defaults to `false`.
As per the spec, `import` and `export` are only allowed to be used at the top
level. When in loose mode these are allowed to be used anywhere.
And by default, when using exports with babel a non-enumerable `__esModule` property
is exported.
```javascript
var foo = exports.foo = 5;
Object.defineProperty(exports, "__esModule", {
value: true
});
```
In environments that don't support this you can enable loose mode on `babel-plugin-transform-es20150-modules-commonjs`
and instead of using `Object.defineProperty` an assignment will be used instead.
```javascript
var foo = exports.foo = 5;
exports.__esModule = true;
```
### `strict`
`boolean`, defaults to `false`
By default, when using exports with babel a non-enumerable `__esModule` property
is exported. In some cases this property is used to determine if the import _is_ the
default export or if it _contains_ the default export.
```javascript
var foo = exports.foo = 5;
Object.defineProperty(exports, "__esModule", {
value: true
});
```
In order to prevent the `__esModule` property from being exported, you can set
the `strict` option to `true`.
### `noInterop`
`boolean`, defaults to `false`
By default, when using exports with babel a non-enumerable `__esModule` property
is exported. This property is then used to determine if the import _is_ the default
export or if it _contains_ the default export.
```javascript
"use strict";
var _foo = require("foo");
var _foo2 = _interopRequireDefault(_foo);
function _interopRequireDefault(obj) {
return obj && obj.__esModule ? obj : { default: obj };
}
```
In cases where the auto-unwrapping of `default` is not needed, you can set the
`noInterop` option to `true` to avoid the usage of the `interopRequireDefault`
helper (shown in inline form above).
|