99 lines
2.3 KiB
Markdown
99 lines
2.3 KiB
Markdown
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# babel-plugin-transform-es2015-arrow-functions
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> Compile ES2015 arrow functions to ES5
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## Example
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**In**
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```javascript
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var a = () => {};
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var a = (b) => b;
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const double = [1,2,3].map((num) => num * 2);
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console.log(double); // [2,4,6]
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var bob = {
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_name: "Bob",
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_friends: ["Sally", "Tom"],
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printFriends() {
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this._friends.forEach(f =>
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console.log(this._name + " knows " + f));
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}
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};
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console.log(bob.printFriends());
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```
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**Out**
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```javascript
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var a = function a() {};
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var a = function a(b) {
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return b;
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};
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var double = [1, 2, 3].map(function (num) {
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return num * 2;
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});
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console.log(double); // [2,4,6]
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var bob = {
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_name: "Bob",
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_friends: ["Sally", "Tom"],
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printFriends: function printFriends() {
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var _this = this;
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this._friends.forEach(function (f) {
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return console.log(_this._name + " knows " + f);
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});
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}
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};
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console.log(bob.printFriends());
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```
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[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)
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## Installation
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```sh
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npm install --save-dev babel-plugin-transform-es2015-arrow-functions
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```
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## Usage
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### Via `.babelrc` (Recommended)
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**.babelrc**
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```js
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// without options
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{
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"plugins": ["transform-es2015-arrow-functions"]
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}
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// with options
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{
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"plugins": [
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["transform-es2015-arrow-functions", { "spec": true }]
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]
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}
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```
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### Via CLI
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```sh
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babel --plugins transform-es2015-arrow-functions script.js
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```
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### Via Node API
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```javascript
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require("babel-core").transform("code", {
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plugins: ["transform-es2015-arrow-functions"]
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});
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```
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## Options
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* `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.
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