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https://github.com/thlorenz/es6ify

browserify >=v2 transform to compile JavaScript.next (ES6) to JavaScript.current (ES5) on the fly.
https://github.com/thlorenz/es6ify

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browserify >=v2 transform to compile JavaScript.next (ES6) to JavaScript.current (ES5) on the fly.

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# es6ify [![build status](https://secure.travis-ci.org/thlorenz/es6ify.png?branch=master)](http://travis-ci.org/thlorenz/es6ify)

[![NPM](https://nodei.co/npm/es6ify.png?downloads=true&stars=true)](https://nodei.co/npm/es6ify/)

[browserify](https://github.com/substack/node-browserify) `>=v2` transform to compile JavaScript.next (ES6) to
JavaScript.current (ES5) on the fly.

```js
browserify({ debug: true })
.add(es6ify.runtime)
.transform(es6ify)
.require(require.resolve('./src/main.js'), { entry: true })
.bundle()
.pipe(fs.createWriteStream(bundlePath));
```

Find the full version of this example [here](https://github.com/thlorenz/es6ify/blob/master/example/build.js).

## Installation

npm install es6ify

## What You Get

![screenshot](https://github.com/thlorenz/es6ify/raw/master/assets/screenshot.png)

[Try it live](http://thlorenz.github.com/es6ify/)

**Table of Contents** *generated with [DocToc](http://doctoc.herokuapp.com/)*

- [Enabling sourcemaps and related posts](#enabling-sourcemaps-and-related-posts)
- [API](#api)
- [Examples](#examples)
- [es6ify.configure(filePattern : Regex)](#es6ifyconfigurefilepattern--regex)
- [es6ify.traceurOverrides](#es6ifytraceuroverrides)
- [Caching](#caching)
- [Source Maps](#source-maps)
- [Supported ES6 features](#supported-es6-features)
- [arrowFunctions](#arrowfunctions)
- [classes](#classes)
- [defaultParameters](#defaultparameters)
- [destructuring](#destructuring)
- [forOf](#forof)
- [propertyMethods](#propertymethods)
- [propertyNameShorthand](#propertynameshorthand)
- [templateLiterals](#templateliterals)
- [restParameters](#restparameters)
- [spread](#spread)
- [generators](#generators)
- [modules](#modules)

## Enabling sourcemaps and related posts

- In Chrome or Firefox: enabled by default
- In IE: works in IE11 onward by default
- [browserify-sourcemaps](http://thlorenz.com/blog/browserify-sourcemaps)
- [html5 rocks sourcemaps post](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/)

## API









e6ify::runtime





The traceur runtime exposed here so it can be included in the bundle via:


browserify.add(es6ify.runtime)


The runtime is quite large and not needed for all ES6 features and therefore not added to the bundle by default.
See this comment for details.




Source:






es6ify::traceurOverrides





Allows to override traceur compiler defaults.


In order to support async functions (async/await) do:


es6ify.traceurOverrides = { asyncFunctions: true }




Source:








es6ify() → {function}





The es6ify transform to be used with browserify.


Example


browserify().transform(es6ify)




Source:



Returns:


function that returns a TransformStream when called with a file





Type


function





es6ify::compileFile(file, src) → {string}





Compile function, exposed to be used from other libraries, not needed when using es6ify as a transform.



Parameters:

Name
Type
Description

file

string

name of the file that is being compiled to ES5

src

string

source of the file being compiled to ES5


Source:



Returns:


compiled source





Type


string





es6ify::configure(filePattern) → {function}





Configurable es6ify transform function that allows specifying the filePattern of files to be compiled.



Parameters:

Name
Type
Argument
Description

filePattern

string

<optional>

(default: `/.js$/) pattern of files that will be es6ified


Source:



Returns:


function that returns a TransformStream when called with a file





Type


function



*generated with [docme](https://github.com/thlorenz/docme)*

## Examples

### es6ify.configure(filePattern : Regex)

The default file pattern includes all JavaScript files, but you may override it in order to only transform files coming
from a certain directory, with a specific file name and/or extension, etc.

By configuring the regex to exclude ES5 files, you can optimize the performance of the transform. However transforming
ES5 JavaScript will work since it is a subset of ES6.

```js
browserify({ debug: true })
.add(require('es6ify').runtime)
// compile all .js files except the ones coming from node_modules
.transform(require('es6ify').configure(/^(?!.*node_modules)+.+\.js$/))
.require(require.resolve('./src/main.js'), { entry: true })
.bundle()
.pipe(fs.createWriteStream(bundlePath));
```

### es6ify.traceurOverrides

Some features supported by traceur are still experimental: either nonstandard, proposed but not yet standardized, or
just too slow to use for most code. Therefore Traceur disables them by default. They can be enabled by overriding these
options.

For instance to support the async functions (`async`/`await`) feature you'd do the following.

```js
var es6ify = require('es6ify');
es6ify.traceurOverrides = { asyncFunctions: true };
browserify({ debug: true })
.add(es6ify.runtime)
.require(require.resolve('./src/main.js'), { entry: true })
.bundle()
.pipe(fs.createWriteStream(bundlePath));
```

## Caching

When es6ify is run on a development server to help generate the browserify bundle on the fly, it makes sense to only
recompile ES6 files that changed. Therefore es6ify caches previously compiled files and just pulls them from there if no
changes were made to the file.

## Source Maps

es6ify instructs the traceur transpiler to generate source maps. It then inlines all original sources and adds the
resulting source map `base64` encoded to the bottom of the transformed content. This allows debugging the original ES6
source when using the `debug` flag with browserify.

If the `debug` flag is not set, these source maps will be removed by browserify and thus will not be contained inside
your production bundle.

## Supported ES6 features

### arrowFunctions

```js
var log = msg => console.log(msg);
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/arrow-functions.js)

### classes

```js
class Character {
constructor(x, y, name) {
this.x = x;
this.y = y;
}
attack(character) {
console.log('attacking', character);
}
}

class Monster extends Character {
constructor(x, y, name) {
super(x, y);
this.name = name;
this.health_ = 100;
}

attack(character) {
super.attack(character);
}

get isAlive() { return this.health > 0; }
get health() { return this.health_; }
set health(value) {
if (value < 0) throw new Error('Health must be non-negative.');
this.health_ = value;
}
}
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/make-monster.js)

### defaultParameters

```js
function logDeveloper(name, codes = 'JavaScript', livesIn = 'USA') {
console.log('name: %s, codes: %s, lives in: %s', name, codes, livesIn);
};
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/default-parameters.js)

### destructuring

```js
var [a, [b], c, d] = ['hello', [', ', 'junk'], ['world']];
console.log(a + b + c); // hello, world
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/destructuring.js)

### forOf

```js
for (let element of [1, 2, 3]) {
console.log('element:', element);
}
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/iterators.js)

### propertyMethods

```js
var object = {
prop: 42,
// No need for function
method() {
return this.prop;
}
};
```

### propertyNameShorthand

```js
var foo = 'foo';
var bar = 'bar';
var obj = { foo, bar };
```

### templateLiterals

```js
var x = 5, y = 10;
console.log(`${x} + ${y} = ${ x + y}`)
// 5 + 10 = 15
```

### restParameters

```js
function printList(listname, ...items) {
console.log('list %s has the following items', listname);
items.forEach(function (item) { console.log(item); });
};
```
[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/rest-parameters.js)

### spread

```js
function add(x, y) {
console.log('%d + %d = %d', x, y, x + y);
}
var numbers = [5, 10]
add(...numbers);
// 5 + 10 = 15
};
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/spread-operator.js)

### generators

```js
// A binary tree class.
function Tree(left, label, right) {
this.left = left;
this.label = label;
this.right = right;
}

// A recursive generator that iterates the Tree labels in-order.
function* inorder(t) {
if (t) {
yield* inorder(t.left);
yield t.label;
yield* inorder(t.right);
}
}

// Make a tree
function make(array) {
// Leaf node:
if (array.length == 1) return new Tree(null, array[0], null);
return new Tree(make(array[0]), array[1], make(array[2]));
}

let tree = make([[['a'], 'b', ['c']], 'd', [['e'], 'f', ['g']]]);
console.log('generating tree labels in order:');

// Iterate over it
for (let node of inorder(tree)) {
console.log(node); // a, b, c, d, ...
}
```

[full example](https://github.com/thlorenz/es6ify/blob/master/example/src/features/generators.js)

### block scoping

```js
{
let tmp = 5;
}
console.log(typeof tmp === 'undefined'); // true
```

### modules

Imports and exports are converted to `commonjs` style `require` and `module.exports` statements to seamlessly integrate
with browserify.