143 lines
3.3 KiB
Markdown
143 lines
3.3 KiB
Markdown
# babel-plugin-transform-es2015-modules-commonjs
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> This plugin transforms ES2015 modules to [CommonJS](http://wiki.commonjs.org/wiki/Modules/1.1).
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>
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> #### Babel 6 Changes
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>
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> Babel 6 changed some behavior by not doing `module.exports = exports['default']` anymore in the modules transforms.
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>
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> There are some caveats, but you can use [babel-plugin-add-module-exports](https://www.npmjs.com/package/babel-plugin-add-module-exports), so that updating to Babel 6 isn't a breaking change since users that don't use ES modules don't have to do `require("your-module").default`.
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>
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> However, it may not match how Node eventually implements ES modules natively given the [the current proposal](https://github.com/nodejs/node-eps/blob/master/002-es-modules.md#46-es-consuming-commonjs).
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## Example
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**In**
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```javascript
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export default 42;
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```
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**Out**
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```javascript
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.default = 42;
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```
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## Installation
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```sh
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npm install --save-dev babel-plugin-transform-es2015-modules-commonjs
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```
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## Usage
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### Via `.babelrc` (Recommended)
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**.babelrc**
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```js
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// without options
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{
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"plugins": ["transform-es2015-modules-commonjs"]
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}
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// with options
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{
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"plugins": [
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["transform-es2015-modules-commonjs", {
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"allowTopLevelThis": true
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}]
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]
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}
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```
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### Via CLI
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```sh
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babel --plugins transform-es2015-modules-commonjs script.js
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```
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### Via Node API
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```javascript
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require("babel-core").transform("code", {
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plugins: ["transform-es2015-modules-commonjs"]
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});
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```
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## Options
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### `loose`
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`boolean`, defaults to `false`.
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As per the spec, `import` and `export` are only allowed to be used at the top
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level. When in loose mode these are allowed to be used anywhere.
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And by default, when using exports with babel a non-enumerable `__esModule` property
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is exported.
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```javascript
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var foo = exports.foo = 5;
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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```
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In environments that don't support this you can enable loose mode on `babel-plugin-transform-es2015-modules-commonjs`
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and instead of using `Object.defineProperty` an assignment will be used instead.
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```javascript
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var foo = exports.foo = 5;
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exports.__esModule = true;
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```
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### `strict`
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`boolean`, defaults to `false`
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By default, when using exports with babel a non-enumerable `__esModule` property
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is exported. In some cases this property is used to determine if the import _is_ the
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default export or if it _contains_ the default export.
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```javascript
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var foo = exports.foo = 5;
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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```
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In order to prevent the `__esModule` property from being exported, you can set
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the `strict` option to `true`.
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### `noInterop`
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`boolean`, defaults to `false`
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By default, when using exports with babel a non-enumerable `__esModule` property
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is exported. This property is then used to determine if the import _is_ the default
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export or if it _contains_ the default export.
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```javascript
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"use strict";
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var _foo = require("foo");
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var _foo2 = _interopRequireDefault(_foo);
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function _interopRequireDefault(obj) {
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return obj && obj.__esModule ? obj : { default: obj };
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}
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```
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In cases where the auto-unwrapping of `default` is not needed, you can set the
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`noInterop` option to `true` to avoid the usage of the `interopRequireDefault`
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helper (shown in inline form above).
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