Babel is a transpiler that let’s you use the JS features of tomorrow, in your applications today. WHY you’d compile? Well, compatabilty for one. You can write code is ES6 and convert it to ES5 (which is fully supported by all browsers).

Transpiling is taking one language and converting it to another. If you have used SASS, you have transpiled SASS code to CSS. Similar with CoffeeScript to generate JS.

Compiling converts one language to another at a lower abstraction level, like Java to bytecode. Transpiling, on the other hand, converts one language to another at the same abstraction level, like SASS to CSS. Both are high level languages that serve the same purposes, i.e. styling HTML.

Babel will convert this newer ES6

var my ArrowFunction = () => "Hello, ES2015.";

to this fully supported ES5

var myArrowFunction = function myArrowFunction() {
    return "Hello, ES2015.";


npm i -D babel-cli

Babel is very modular. So not only will you install the Babel module (bable-core) to get started with, you’ll also install other modules for Babel like presets (babel-preset-react) etc.

  • babel-core is Babel itself
  • babel-loader is a Webpack loader or Babel
  • babel-preset-react is a React preset module for Babel

Configuration (babelrc)

babelrc the Babel configuration file, is just another JSON file. The two most important properties are plugins and presets.

  • Plugins is the features you want to use, like arrow function, ES2015 constants.
  • Presets bundle multiple plugins together, so instead of specifying plugins manually, you can use all ES2015 features by using babel-preset-es2015.

You can install Babel’s ES2015 preset with

npm i -D babel-preset-es2015
    "presets": [
    "pugins": []

Manual conversion

define a build command in the script section in package.json

"scripts": {
    "build": "babel src -d build" // 

we want to take index.js from src dir, convert it, place in build dir. the babel command takes two args, the name of file/dir to be transpiled, and the dir where it should place the converted files. -d is for dirs.

run build:

npm run build


You can use Gulp, Grunt, Webpack or something similar