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  • License MIT

Compile ES2015 arrow functions to ES5

Package Exports

  • babel-plugin-transform-es2015-arrow-functions

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (babel-plugin-transform-es2015-arrow-functions) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

babel-plugin-transform-es2015-arrow-functions

Compile ES2015 arrow functions to ES5

Example

In

var a = () => {};
var a = (b) => b;

const double = [1,2,3].map((num) => num * 2);
console.log(double); // [2,4,6]

var bob = {
  _name: "Bob",
  _friends: ["Sally", "Tom"],
  printFriends() {
    this._friends.forEach(f =>
      console.log(this._name + " knows " + f));
  }
};
console.log(bob.printFriends());

Out

var a = function () {};
var a = function (b) {
  return b;
};

const double = [1, 2, 3].map(function (num) {
  return num * 2;
});
console.log(double); // [2,4,6]

var bob = {
  _name: "Bob",
  _friends: ["Sally", "Tom"],
  printFriends() {
    var _this = this;

    this._friends.forEach(function (f) {
      return console.log(_this._name + " knows " + f);
    });
  }
};
console.log(bob.printFriends());

Installation

npm install --save-dev babel-plugin-transform-es2015-arrow-functions

Usage

.babelrc

Without options:

{
  "plugins": ["transform-es2015-arrow-functions"]
}

With options:

{
  "plugins": [
    ["transform-es2015-arrow-functions", { "spec": true }]
  ]
}

Via CLI

babel --plugins transform-es2015-arrow-functions script.js

Via Node API

require("babel-core").transform("code", {
  plugins: ["transform-es2015-arrow-functions"]
});

Options

spec

boolean, defaults to false.

Example

Using spec mode with the above example produces:

var _this = this;

var a = function a() {
  babelHelpers.newArrowCheck(this, _this);
}.bind(this);
var a = function a(b) {
  babelHelpers.newArrowCheck(this, _this);
  return b;
}.bind(this);

const double = [1, 2, 3].map(function (num) {
  babelHelpers.newArrowCheck(this, _this);
  return num * 2;
}.bind(this));
console.log(double); // [2,4,6]

var bob = {
  _name: "Bob",
  _friends: ["Sally", "Tom"],
  printFriends() {
    var _this2 = this;

    this._friends.forEach(function (f) {
      babelHelpers.newArrowCheck(this, _this2);
      return console.log(this._name + " knows " + f);
    }.bind(this));
  }
};
console.log(bob.printFriends());

This option enables the following:

  • Wrap the generated function in .bind(this) and keeps uses of this inside the function as-is, instead of using a renamed this.

  • Add a runtime check to ensure the functions are not instantiated.

  • Add names to arrow functions.