Using Babel

In the browser

With babel-standalone

<div id="output"></div>
<!-- Load Babel -->
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
<!-- Your custom script here -->
<script type="text/babel">
const getMessage = () => "Hello World";
document.getElementById('output').innerHTML = getMessage();
</script>

CLI

Instead of running Babel directly from the command line we’re going to put our commands in npm scripts which will use our local version.

Simply add a "scripts" field to your package.json and put the babel command inside there as build.

  {
    "name": "my-project",
    "version": "1.0.0",
+   "scripts": {
+     "build": "babel src -d lib"
+   },
    "devDependencies": {
      "babel-cli": "^6.0.0"
    }
  }

Now from our terminal we can run:

npm run build

This will run Babel the same way as before and the output will be present in lib directory, only now we are using a local copy.

Alternatively, you can reference the babel cli inside of node_modules.

./node_modules/.bin/babel src -d lib

For full documentation on the Babel CLI see the usage docs.

Require hook

To include it you will need to require it at the top of the entry point to your application.

require("babel-register");

If you are using ES6’s import syntax in your application’s entry point, you should instead import at the top of the entry point to ensure it is loaded first:

import "babel-register";

All subsequent files required by node with the extensions .es6, .es, .jsx and .js will be transformed by Babel. The polyfill specified in polyfill is also automatically required.

Not suitable for libraries

The require hook automatically hooks itself into all node requires. This will pollute the global scope and introduce conflicts. Because of this it's not suitable for libraries, if however you're writing an application then it's completely fine to use.

Not meant for production use

The require hook is primarily recommended for simple cases.

For full documentation on the Babel require hook see the usage docs.

Broccoli

var babelTranspiler = require("broccoli-babel-transpiler");
var scriptTree = babelTranspiler(inputTree, options);

For more information see the babel/broccoli-babel-transpiler repo.

Browserify

Via CLI

browserify script.js -t babelify --outfile bundle.js

Via Node API

browserify({ debug: true })
  .transform(babelify);

Or a more complete example:

var fs = require("fs");
var browserify = require("browserify");
var babelify = require("babelify");

browserify({ debug: true })
  .transform(babelify)
  .require("./script.js", { entry: true })
  .bundle()
  .on("error", function (err) { console.log("Error: " + err.message); })
  .pipe(fs.createWriteStream("bundle.js"));

Passing options

CLI

browserify -d -e script.js -t [ babelify --comments false ]

Node API

browserify().transform(babelify.configure({
  comments: false
}))

package.json

{
  "transform": [["babelify", { "comments": false }]]
}

For more information see the babel/babelify repo.

Brunch

That’s it! Set babel options in your brunch config (such as brunch-config.coffee) except for filename and sourceMap which are handled internally.

plugins:
  babel:
    whitelist: ["arrowFunctions"]
    format:
      semicolons: false

For more information see the babel/babel-brunch repo.

Duo

Via CLI

duo --use duo-babel

Via Node API

Duo(root)
  .entry(entry)
  .use(babel)
  .run(fn);

For more information see the babel/duo-babel repo.

Gobble

var gobble = require("gobble");
module.exports = gobble("src").transform("babel", options);

For more information see the babel/gobble-babel repo.

Grunt

require("load-grunt-tasks")(grunt); // npm install --save-dev load-grunt-tasks

grunt.initConfig({
  "babel": {
    options: {
      sourceMap: true
    },
    dist: {
      files: {
        "dist/app.js": "src/app.js"
      }
    }
  }
});

grunt.registerTask("default", ["babel"]);

For more information see the babel/grunt-babel repo.

Gulp

var gulp = require("gulp");
var babel = require("gulp-babel");

gulp.task("default", function () {
  return gulp.src("src/app.js")
    .pipe(babel())
    .pipe(gulp.dest("dist"));
});

With source maps

Use gulp-sourcemaps like this:

var gulp = require("gulp");
var sourcemaps = require("gulp-sourcemaps");
var babel = require("gulp-babel");
var concat = require("gulp-concat");

gulp.task("default", function () {
  return gulp.src("src/**/*.js")
    .pipe(sourcemaps.init())
    .pipe(babel())
    .pipe(concat("all.js"))
    .pipe(sourcemaps.write("."))
    .pipe(gulp.dest("dist"));
});

For more information see the babel/gulp-babel repo.

jspm

Babel will automatically be used when loading any source with import or export module syntax.

JSX support is currently disabled by jspm. To re-enable it, add `"blacklist": []` to `babelOptions` in the jspm configuration file.

Make

SRC = $(wildcard src/*.js)
LIB = $(SRC:src/%.js=lib/%.js)

lib: $(LIB)
lib/%.js: src/%.js .babelrc
  mkdir -p $(@D)
  babel $< -o $@

make

MSBuild

Import the task in your MSBuild script:

<UsingTask AssemblyFile="packages\React.MSBuild.2.1.0\React.MSBuild.dll" TaskName="TransformBabel" />

Use it:

<TransformBabel SourceDir="$(MSBuildProjectDirectory)" TargetDir="" />

This will transform every .js and .jsx file in the directory, and output a .generated.js file alongside it.

See the guide for more information

RequireJS

Add the following paths to your configuration:

paths: {
  es6: "node_modules/requirejs-babel/es6",
  babel: "node_modules/requirejs-babel/babel-4.6.6.min"
}

Then reference files via the es6! plugin name:

define(["es6!your-es6-module"], function (module) {
  // ...
});

For more information see the mikach/requirejs-babel repo.

Rollup

var rollup = require("rollup");
var babel = require("rollup-plugin-babel");

rollup.rollup({
  entry: "src/main.js",
  plugins: [ babel() ]
}).then(function (bundle) {
  bundle.write({
    dest: "dist/bundle.js",
    format: "umd"
  });
});

For more information see the rollup and rollup-plugin-babel repos.

Sprockets

# Gemfile
gem "sprockets"
gem "sprockets-es6"

require "sprockets/es6"

For more information see the TannerRogalsky/sprockets-es6 repo.

Webpack

Via config

module: {
  rules: [
    { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" }
  ]
}

Via loader

var Person = require("babel!./Person.js").default;
new Person();

For more information see the babel/babel-loader repo.

Webpack 1

Via config

module: {
  loaders: [
    { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" }
  ]
}

Via loader

var Person = require("babel!./Person.js").default;
new Person();

For more information see the babel/babel-loader repo.

Fly

  export function* text () {
    yield this
      .source("src/**/*.js")
      .babel({ presets: ["env"] })
      .target("dist/")
  }

For more information see the flyjs/fly-babel repo.

Start

import Start from 'start';
import reporter from 'start-pretty-reporter';
import files from 'start-files';
import read from 'start-read';
import babel from 'start-babel';
import write from 'start-write';

const start = Start(reporter());

export function build() {
  return start(
    files('lib/**/*.js'),
    read(),
    babel({ sourceMaps: true }),
    write('build/')
  );
}

For more information see the start-runner/babel repo.

Ember

That’s it!

For more information see the babel/ember-cli-babel repo.

Meteor

That’s it! Any files with a .js extension will automatically be compiled with Babel.

As of Meteor 1.2, the ecmascript package is installed by default for all new apps, so meteor add ecmascript is only necessary for existing apps.

For more information see the ecmascript README.md.

Rails

# Gemfile
gem "sprockets"
gem "sprockets-es6"

require "sprockets/es6"

For more information see the TannerRogalsky/sprockets-es6 repo.

Sails

That’s it!

For more information see the artificialio/sails-hook-babel repo.

AVA

AVA ships with ES2015 support built-in using Babel 6 under the hood, so you can write test using ES2015 syntax right away.

The AVA default Babel configuration includes the "es2015" and "stage-2" presets, but you can customize any Babel option for transpiling test files with the "babel" option in AVA’s package.json configuration.

For example:

{
  "ava": {
    "babel": {
      "presets": [
        "es2015",
        "react"
      ]
    }
  }
}

Or you can simply "inherit" the Babel configuration from .babelrc or Babel’s package.json configuration, making test files use the same configuration as your source files:

{
  "ava": {
    "babel": "inherit"
  }
}

Note that AVA always adds a few custom Babel plugins when transpiling your plugins see notes.

For more information see the AVA recipe on how to configure Babel.

Jasmine

In your spec/support/jasmine.json file make the following changes:

{
  "helpers": [
    "../node_modules/babel-register/lib/node.js"
  ]
}

This file is created when you setup a project with the jasmine init command.

For more information see the piecioshka/test-jasmine-babel repo.

Jest

In your package.json file make the following changes:

{
  "scripts": {
    "test": "jest"
  },
  "jest": {
    "transform": {
      "^.+\\.jsx?$": "babel-jest"
    }
  }
}

For more information see the babel/babel-jest repo.

Karma

module.exports = function(config) {
  config.set({
    files: [
      "src/**/*.js",
      "test/**/*.js"
    ],
    preprocessors: {
      "src/**/*.js": ["babel"],
      "test/**/*.js": ["babel"]
    },
    "babelPreprocessor": {
      // options go here
    }
  });
};

For more information see the babel/karma-babel-preprocessor repo.

Lab

When running tests with lab set the transpiler to lab-babel:

lab -T node_modules/lab-babel

Mocha

Mocha 4

--compilers is deprecated as of Mocha v4.0.0. See further explanation and workarounds.

In your package.json file make the following changes:

{
  "scripts": {
    "test": "mocha --require babel-register"
  }
}

Some features will require a polyfill:

npm install --save-dev babel-polyfill

{
  "scripts": {
    "test": "mocha --require babel-polyfill --require babel-register"
  }
}

Mocha 3

{
  "scripts": {
    "test": "mocha --compilers js:babel-register"
  }
}

With polyfill:

{
  "scripts": {
    "test": "mocha --require babel-polyfill --compilers js:babel-register"
  }
}

Connect

var babelMiddleware = require("babel-connect");

app.use(babelMiddleware({
  options: {
    // options to use when transforming files
  },
  src: "assets",
  dest: "cache"
}));

app.use(connect.static("cache"));

For more information see the babel/babel-connect repo.

Nodemon

In your package.json file make the following changes:

{
  "scripts": {
    "babel-node": "babel-node --presets=/*a*/ --ignore='foo|bar|baz'"
  }
}

Then call your script with:

nodemon --exec npm run babel-node -- path/to/script.js

Arguments caveat

Calling nodemon with babel-node may lead to arguments getting parsed incorrectly if you forget to use a double dash. Using npm-scripts helpers prevent this. If you chose to skip using npm-scripts, it can be expressed as:

nodemon --exec babel-node --presets=es2015 --ignore='foo\|bar\|baz' -- path/to/script.js

C# / .NET

var babel = ReactEnvironment.Current.Babel;
// Transpiles a file
// You can instead use `TransformFileWithSourceMap` if you want a source map too.
var result = babel.TransformFile("foo.js");
// Transpiles a piece of code
var result = babel.Transform("class Foo { }");

Node

require("babel-core").transform("code", options);

For full documentation on the Babel API see the usage docs.

Ruby

require 'babel/transpiler'
Babel::Transpiler.transform File.read("foo.es6")

For more information see the babel/ruby-babel-transpiler repo.

Pug

Now you can use ES6 in your pug templates as following.

script
  :babel
    console.log("Hello World !!!");
    class Person {
      constructor(name) {
        this.name = name;
      }
      sayName(){
        console.log(`Hello, my name is ${this.name}`);
      }
    }
    var person = new Person("Apoxx");
    person.sayName();

For more information see the jstransformers/jstransformer-babel repo.

WebStorm

In Preferences - Tools - File watchers, click + button and select Babel file watcher from the list.

Specify the path to Babel executable and click Ok.

By default all files with a .js extension will be automatically compiled with Babel upon change. The generated ES5 files and source maps will be saved next to original files.

Lastly, in Languages & Frameworks - JavaScript - JavaScript language version, choose ECMAScript 6.

For more information see the post in the WebStorm blog.

Node Inspector

babel-node-debug path/to/script.js

Or use the alias:

bode-debug path/to/script.js

For more information see the crabdude/babel-node-debug repo.