Node.js can be easily installed by visiting the official Node website and accessing the Downloads section at http://nodejs.org/download/.
Once there, be sure to download the correct version depending on your OS and CPU (32 bit or 64 bit).
Mac OS X installation instructions
To determine which version of Node you want to download, you first need to determine your processor type: 32 or 64 bit. You can do this by executing the following command from a terminal:
$ sysctl hw | grep 64bit hw.cpu64bit_capable: 1
If you get
1 in the response, then you are running a 64-bit CPU. If the response is
0, then you are running the 32-bit version. Fortunately, there is a universal installer specifically for Mac available from the Node website; however, ...