es6-arrow-function

Compiles JavaScript written using arrow functions to use ES5-compatible function syntax. For example, this:

[1, 2, 3].map(n => n * 2);

compiles to this:

[1, 2, 3].map(function(n) { return n * 2; });

For more information about the proposed syntax, see the TC39 wiki page on arrow functions.

Install

$ npm install es6-arrow-function

Usage

$ node
> var compile = require('es6-arrow-function').compile;
[Function]

Without arguments:

> compile('$(() => main());');
'$(function() { return main(); });'

With a single argument:

> compile('[1, 2, 3].map(n => n * 2);');
'[1, 2, 3].map(function(n) { return n * 2; });'

With multiple arguments:

> compile('[1, 2, 3].map((n, i) => n * i);');
'[1, 2, 3].map(function(n, i) { return n * i; });'

It binds the current context:

> compile('stream.on("data", d => this.data += d);');
'stream.on("data", (function(d) { return this.data += d; }).bind(this));'

Or work directly with the AST:

$ cat ast.json
{
  "type": "Program",
  "body": [
    {
      "type": "ExpressionStatement",
      "expression": {
        "type": "CallExpression",
        "callee": {
          "type": "Identifier",
          "name": "$"
        },
        "arguments": [
          {
            "type": "ArrowFunctionExpression",
            "id": null,
            "params": [],
            "defaults": [],
            "body": {
              "type": "CallExpression",
              "callee": {
                "type": "Identifier",
                "name": "main"
              },
              "arguments": []
            },
            "rest": null,
            "generator": false,
            "expression": true
          }
        ]
      }
    }
  ]
}
$ node
> var transform = require('es6-arrow-function').transform;
[Function]
> console.log JSON.stringify(transform(require('./ast.json')), null, 2);
{
  "type": "Program",
  "body": [
    {
      "type": "ExpressionStatement",
      "expression": {
        "type": "CallExpression",
        "callee": {
          "type": "Identifier",
          "name": "$"
        },
        "arguments": [
          {
            "type": "FunctionExpression",
            "id": null,
            "params": [],
            "defaults": [],
            "body": {
              "type": "BlockStatement",
              "body": [
                {
                  "type": "ReturnStatement",
                  "argument": {
                    "type": "CallExpression",
                    "callee": {
                      "type": "Identifier",
                      "name": "main"
                    },
                    "arguments": []
                  }
                }
              ]
            },
            "rest": null,
            "generator": false,
            "expression": false
          }
        ]
      }
    }
  ]
}

Command line

If installing via npm a command line tool will be available called es6-arrow-function.

$ echo "()=>123" | es6-arrow-function
(function () {
  return 123;
});

$ es6-arrow-function $file
(function () {
  return 123;
});

Browserify

Browserify support is built in.

$ npm install es6-arrow-function  # install local dependency
$ browserify -t es6-arrow-function $file
// BOILERPLATE
(function () {
  return 123;
});

Contributing

Setup

First, install the development dependencies:

$ npm install

Then, try running the tests:

$ npm test

Pull Requests

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

Any contributors to the master es6-arrow-function repository must sign the Individual Contributor License Agreement (CLA). It's a short form that covers our bases and makes sure you're eligible to contribute.

When you have a change you'd like to see in the master repository, send a pull request. Before we merge your request, we'll make sure you're in the list of people who have signed a CLA.

pdubroy/es6-arrow-function