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node_modules/babel-plugin-transform-es2015-arrow-functions/README.md 2.35 KB
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  # babel-plugin-transform-es2015-arrow-functions
  
  > Compile ES2015 arrow functions to ES5
  
  ## Example
  
  **In**
  
  ```javascript
  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**
  
  ```javascript
  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
  
  ```sh
  npm install --save-dev babel-plugin-transform-es2015-arrow-functions
  ```
  
  ## Usage
  
  ### Via `.babelrc` (Recommended)
  
  **.babelrc**
  
  ```js
  // without options
  {
    "plugins": ["transform-es2015-arrow-functions"]
  }
  
  // with options
  {
    "plugins": [
      ["transform-es2015-arrow-functions", { "spec": true }]
    ]
  }
  ```
  
  ### Via CLI
  
  ```sh
  babel --plugins transform-es2015-arrow-functions script.js
  ```
  
  ### Via Node API
  
  ```javascript
  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.