Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.¹

Installation

Node.js may be installed via three major methods on Ubuntu and its official derivatives.

Via APT

The first method is via APT (or by the front-end, the Ubuntu Software Center) by running:

sudo apt-get install nodejs

the problem, however, is that Node.js installed this way is usually very out of date.

Via APT, cURL and nodesource

Alternately, Node.js may be installed via running:

sudo apt-get install -y curl
curl -sL https://deb.nodesource.com/setup_0.12 | sudo bash -
sudo apt-get install -y nodejs

The version provided via this method is usually up to date and even when it is not it is usually only out of date by at most a few days. This installation will be automatically updated whenever one runs Software Updater.

From source

If one requires the very latest version, or another version that is not available by either of these two methods one can install from source code. This is usually the most time-consuming of methods, potentially taking over an hour, depending on one's platform, although most of this is automated requiring very little user input. To get the source code one can go to http://nodejs.org/dist/, to find a URL for the release they want (which is http://nodejs.org/dist/latest/node-$ver.tar.gz for the latest release, where $ver is replaced with the latest available version with the letter v in front of it, for example, $ver=v0.12.7 for version 0.12.7). One can then download this release from one's web browser, via filezilla, via wget or via whatever download manager one would prefer. For simplicity's sake the next code assumes one is downloading the tarball for Node.js version 0.5.1+ via wget, in which case the code is (run from the directory to which you want the source code downloaded):

#Install the dependencies; if you are installing Node.js 0.6.x you will also
#need libssl-dev
sudo apt-get install build-essential python
#Setting the version one is installing, remember the v!
ver=v0.12.7
wget -c http://nodejs.org/dist/$ver/node-$ver.tar.gz
tar -xzf node-$ver.tar.gz
cd node-$ver
./configure
make
sudo make install

note that at the tar line one can specify where the source code is extracted to if one wishes (via adding -C DESTDIR where DESTDIR is the destination of the source code), but if one does one will need to adjust the next line to cd DESTDIR. This installation may be more flexible than the previously-outlined methods but it will not automatically update itself. Instead to update a source installation one will need to re-run lines 5-10 with the updated ver value.

If one anticipates updating Node.js manually often (e.g., if one wants the latest release of Node.js as soon as it is released) it may be best to use git instead to get the source code. Although this method will take up more hard disk drive (HDD) space and is a larger download (>100 MB), hence it is only recommended for those planning to update their Node.js installation regularly.

To get the source code via git and then install it run:

sudo apt-get install git #Installing git
git clone https://github.com/joyent/node.git
cd node
git remote add upstream https://github.com/joyent/node.git
#Again, replace this with the latest available release
ver=v0.12.7
git fetch upstream
git checkout $ver
./configure
make
sudo make install

then to update this installation re-run the last 6 lines (from ver=v0.12.7 down) of this code, with an updated ver value.

References

1. nodejs.org