To install Node.js, you need to go to the http://nodejs.org where you can download a pre-compiled binary package which is easy to install. I'm going for version 6 with latest features.
You can install the package from the downloaded dmg file. The installation wizard will install Node.js and the npm (Node Package Manager) which is the default package manager for Node.js. Well, this 14MB downloaded file will take nearly 47MB of installation space from your machine. Completion of the installation, check whether the /usr/local/bin is added to your path. Type echo $PATH is the terminal.
This is my first step with Node, along way to go.