gulp-es6-module-to-closure
==========================

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compile ES6 `import/export` => Google Closure `goog.require/goog.provide`

__Attention:__ For supporting ES6 features, some special rules are introduced.
See examples below, especially if you use translated library from existing code.


## Install

```shell
npm install gulp-es6-module-to-closure --save-dev
```


## Usage

```javascript
var es6ModuleToClosure = require("gulp-es6-module-to-closure");

gulp.src("./src/**/*.js")
  .pipe(es6ModuleToClosure({
    root: 'src',
    namespace: "prefix.name.space"
  }))
  .pipe(gulp.dest("./dist"));
```


## Example

### export

- Compiling `${srcDir}/ns/file-name.js`
  ```javascript
export var foo = 'FOO';
```
  with namespace `com.xxx` will generate
  ```javascript
goog.provide("com.xxx.ns.filename.foo");
goog.scope(function() {
    com.xxx.ns.filename.foo = 'FOO';
});
```
at `${distDir}/ns/file-name.js`.


- Compiling `${srcDir}/ns/file-name.js`
  ```javascript
export default 'FOO';
```
  with namespace `com.xxx` will generate
  ```javascript
goog.provide("com.xxx.ns.filename.default");
goog.scope(function() {
    com.xxx.ns.filename.default = 'FOO';
});
```
  at `${distDir}/ns/file-name.js`.


### import

- Compiling `${srcDir}/ns/app.js`
  ```javascript
import {foo} from './file-name.js';
```
  with namespace `com.xxx` will generate
  ```javascript
goog.require("com.xxx.ns.filename.foo");
goog.scope(function() {
    var foo = com.xxx.ns.filename.foo;
});
```
  at `${distDir}/ns/app.js`.


- Compiling `${srcDir}/ns/app.js`
  ```javascript
import foo from './file-name.js';
```
  with namespace `com.xxx` will generate
  ```javascript
goog.require("com.xxx.ns.filename.default");
goog.scope(function() {
    var foo = com.xxx.ns.filename.default;
});
```
  at `${distDir}/ns/app.js`.


## Supported Syntax

Following table is made from Draft October 14, 2014.

https://people.mozilla.org/~jorendorff/es6-draft.html#sec-static-and-runtme-semantics-module-records

### import

| Syntax                                            | supported |
|:--------------------------------------------------|:---------:|
| import v from "mod";                              |    ✓     |
| import * as ns from "mod";                        |    ✓     |
| import {x} from "mod";                            |    ✓     |
| import {x as v} from "mod"; {x} from "mod";       |    ✓     |

### export

| Syntax                                            | supported |
|:--------------------------------------------------|:---------:|
| export var v;                                     |    ✓     |
| export default function f(){};                    |    ✓     |
| export default function(){};                      |    ✓     |
| export default 42;                                |    ✓     |
| export {x};                                       |    ✓     |
| export {v as x};                                  |    ✓     |
| export {x} from "mod";                            |          |
| export {v as x} from "mod";                       |          |
| export * from "mod";                              |          |

## Migration

### v0.x.x => v1.x.x

Reference from manual code to generated code is changed.

Before:
```
goog.require('name.space.varName');
```
After:
```
goog.require('name.space.fileName.varName');
```