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babel-plugin-transform-es2015-arrow-functions

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 a() {};
var a = function a(b) {
  return b;
};
 
var double = [1, 2, 3].map(function (num) {
  return num * 2;
});
console.log(double); // [2,4,6] 
 
var bob = {
  _name: "Bob",
  _friends: ["Sally", "Tom"],
  printFriends: function printFriends() {
    var _this = this;
 
    this._friends.forEach(function (f) {
      return console.log(_this._name + " knows " + f);
    });
  }
};
console.log(bob.printFriends());

[Try in REPL](http://babeljs.io/repl/#?evaluate=true&lineWrap=true&presets=es2015%2Ces2015-loose&experimental=false&loose=false&spec=false&code=var%20a%20%3D%20()%20%3D%3E%20%7B%7D%3B%0Avar%20a%20%3D%20(b)%20%3D%3E%20b%3B%0A%0Aconst%20double%20%3D%20%5B1%2C2%2C3%5D.map((num)%20%3D%3E%20num%20*%202)%3B%0Aconsole.log(double)%3B%20%2F%2F%20%5B2%2C4%2C6%5D%0A%0Avar%20bob%20%3D%20%7B%0A%20%20_name%3A%20%22Bob%22%2C%0A%20%20_friends%3A%20%5B%22Sally%22%2C%20%22Tom%22%5D%2C%0A%20%20printFriends()%20%7B%0A%20%20%20%20this._friends.forEach(f%20%3D%3E%0A%20%20%20%20%20%20console.log(this._name%20%2B%20%22%20knows%20%22%20%2B%20f))%3B%0A%20%20%7D%0A%7D%3B%0Aconsole.log(bob.printFriends())%3B&playground=true)

Installation

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

Usage

Via .babelrc (Recommended)

.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 - This option wraps the generated function in .bind(this) and keeps uses of this inside the function as-is, instead of using a renamed this. It also adds a runtime check to ensure the functions are not instantiated.