Sunday, January 3, 2016

Installing Babel command line and playing with ES6

If you would like to play with ECMAScript6, you can install Babel CLI globally on your machine and run the babel-node command. babel-node is a version of the Node.js executable that understands ES6. It can be installed with the package manager NPM. Installation instructions are listed below.

1) Install two Node.js modules babel and babel-cli one after another. Note: if you have some troubles during installation, update your Node.js and NPM to the latest stable versions.

npm install --global babel
npm install --global babel-cli

2) Install a set of plugins for available ES6 (ES2015) features. Without these plugins you will get errors about unexpected token or similar. See for more details about supported ES6 features.

npm install --global babel-preset-es2015

3a) Start interactive REPL and type ES6 code. Note: globally installed modules on Windows are located under C:\Users\<Username>\AppData\Roaming\npm\node_modules, so that we need to put a complete path to them.

babel-node --presets C:\\Users\\Oleg\\AppData\\Roaming\\npm\\node_modules\\babel-preset-es2015
> let arr = [1,2,3]
> => x * x)
Output: [1,4,9]

3b) Alternative, you can place some ES6 code into a file, e.g. testes6.js, and let it run.

babel-node --presets C:\\Users\\Oleg\\AppData\\Roaming\\npm\\node_modules\\babel-preset-es2015 testes6.js
Output: [1,4,9]

In the example, babel-node is executed in the same directory where the file testes6.js is located.