The preferred method for installing Node.js, now, is to use the versions available in package managers, such as
apt-get, or Macports. Package managers simplify your life by helping to maintain the current version of the software on your computer, ensuring to update dependent packages as necessary, all by typing a simple command such as
apt-get update. Let's go over this first.
The MacPorts project (http://www.macports.org/) has for years been packaging a long list of open source software packages for Mac OS X, and they have packaged Node.js. After you have installed MacPorts using the installer on their website, installing Node.js is pretty much this simple:
$ sudo port ...