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How to Install Node.js on Ubuntu 18.04


Node.js is a JavaScript platform for general-purpose programming that allows users to build network applications quickly. By leveraging JavaScript on both the front and backend, Node.js makes development more consistent and integrated.


Prerequisites
This tutorial assumes that you are using Ubuntu 18.04. Before you begin, you should have a non-root user account with sudo privileges set up on your system. You can learn how to do this by following the basic server setup guide for Ubuntu 18.04.


Installing the Distro-Stable Version for Ubuntu
Ubuntu 18.04 contains a version of Node.js in its default repositories that can be used to provide a consistent experience across multiple systems. At the time of writing, the version in the repositories is 8.10.0. This will not be the latest version, but it should be stable and sufficient for quick experimentation with the language.

To get this version, you can use the apt package manager. Refresh your local package index by typing:

sudo apt update

Install Node.js from the repositories:

sudo apt install nodejs

If the package in the repositories suits your needs, this is all you need to do to get set up with Node.js. In most cases, you'll also want to also install npm, the Node.js package manager. You can do this by typing:

sudo apt install npm

This will allow you to install modules and packages to use with Node.js.

Because of a conflict with another package, the executable from the Ubuntu repositories is called nodejs instead of node. Keep this in mind as you are running software.

To check which version of Node.js you have installed after these initial steps, type:

nodejs -v

Once you have established which version of Node.js you have installed from the Ubuntu repositories, you can decide whether or not you would like to work with different versions, package archives, or version managers. Next, we'll discuss these elements, along with more flexible and robust methods of installation.


Installing Using a PPA
To get a more recent version of Node.js you can add the PPA (personal package archive) maintained by NodeSource. This will have more up-to-date versions of Node.js than the official Ubuntu repositories, and will allow you to choose between Node.js v6.x (supported until April of 2019), Node.js v8.x (the current LTS version, supported until December of 2019), and Node.js v10.x (the latest version, supported until April of 2021).

First, install the PPA in order to get access to its contents. From your home directory, use curl to retrieve the installation script for your preferred version, making sure to replace 10.x with your preferred version string (if different):

cd ~
curl -sL https://deb.nodesource.com/setup_10.x -o nodesource_setup.sh

You can inspect the contents of this script with nano (or your preferred text editor):

nano nodesource_setup.sh

Run the script under sudo:

sudo bash nodesource_setup.sh

The PPA will be added to your configuration and your local package cache will be updated automatically. After running the setup script from Nodesource, you can install the Node.js package in the same way you did above:

sudo apt install nodejs

To check which version of Node.js you have installed after these initial steps, type:

nodejs -v

Output
v10.0.0

The nodejs package contains the nodejs binary as well as npm, so you don't need to install npm separately.

npm uses a configuration file in your home directory to keep track of updates. It will be created the first time you run npm. Execute this command to verify that npm is installed and to create the configuration file:

npm -v

Output
5.6.0

In order for some npm packages to work (those that require compiling code from source, for example), you will need to install the build-essential package:

sudo apt install build-essential

You now have the necessary tools to work with npm packages that require compiling code from source.


Installing Using NVM
An alternative to installing Node.js through apt is to use a specially designed tool called nvm, which stands for "Node.js Version Manager". Rather than working at the operating system level, nvm works at the level of an independent directory within your home directory. This means that you can install multiple self-contained versions of Node.js without affecting the entire system.

Controlling your environment with nvm allows you to access the newest versions of Node.js and retain and manage previous releases. It is a different utility from apt, however, and the versions of Node.js that you manage through it are distinct from the distro-stable version of Node.js available from the Ubuntu repositories.

To download the nvm installation script from the project's GitHub page, you can use curl. Note that the version number may differ from what is highlighted here:

curl -sL https://raw.githubusercontent.com/creationix/nvm/v0.33.11/install.sh -o install_nvm.sh

Inspect the installation script with nano:

nano install_nvm.sh

Run the script with bash:

bash install_nvm.sh

It will install the software into a subdirectory of your home directory at ~/.nvm. It will also add the necessary lines to your ~/.profile file to use the file.

To gain access to the nvm functionality, you'll need to either log out and log back in again or source the ~/.profile file so that your current session knows about the changes:

source ~/.profile

With nvm installed, you can install isolated Node.js versions. For information about the versions of Node.js that are available, type:

nvm ls-remote

Output
...
 v8.11.1   (Latest LTS: Carbon)
 v9.0.0
 v9.1.0
 v9.2.0
 v9.2.1
 v9.3.0
 v9.4.0
 v9.5.0
 v9.6.0
 v9.6.1
 v9.7.0
 v9.7.1
 v9.8.0
 v9.9.0
v9.10.0
v9.10.1
v9.11.0
v9.11.1
v10.0.0 

As you can see, the current LTS version at the time of this writing is v8.11.1. You can install that by typing:

nvm install 8.11.1

Usually, nvm will switch to use the most recently installed version. You can tell nvm to use the version you just downloaded by typing:

nvm use 8.11.1

When you install Node.js using nvm, the executable is called node. You can see the version currently being used by the shell by typing:

node -v

Output
v8.11.1

If you have multiple Node.js versions, you can see what is installed by typing:

nvm ls

If you wish to default one of the versions, type:

nvm alias default 8.11.1

This version will be automatically selected when a new session spawns. You can also reference it by the alias like this:

nvm use default

Each version of Node.js will keep track of its own packages and has npm available to manage these.

You can have npm install packages to the Node.js project's ./node_modules directory. Use the following syntax to install the express module:

npm install express

If you'd like to install the module globally, making it available to other projects using the same version of Node.js, you can add the -g flag:

npm install -g express

This will install the package in:

~/.nvm/versions/node/node_version/lib/node_modules/express

Installing the module globally will let you run the commands from the command line, but you'll have to link the package into your local sphere to require it from within a program:

npm link express

You can learn more about the options available to you with nvm by typing:

nvm help


Removing Node.js
You can uninstall Node.js using apt or nvm, depending on the version you want to target. To remove the distro-stable version, you will need to work with the apt utility at the system level.

To remove the distro-stable version, type the following:

sudo apt remove nodejs

This command will remove the package and retain the configuration files. These may be of use to you if you intend to install the package again at a later point. If you don’t want to save the configuration files for later use, then run the following:

sudo apt purge nodejs

This will uninstall the package and remove the configuration files associated with it.

As a final step, you can remove any unused packages that were automatically installed with the removed package:

sudo apt autoremove

To uninstall a version of Node.js that you have enabled using nvm, first determine whether or not the version you would like to remove is the current active version:

nvm current

If the version you are targeting is not the current active version, you can run:

nvm uninstall node_version

This command will uninstall the selected version of Node.js.

If the version you would like to remove is the current active version, you must first deactivate nvm to enable your changes:

nvm deactivate

You can now uninstall the current version using the uninstall command above, which will remove all files associated with the targeted version of Node.js except the cached files that can be used for reinstallation.


Wrapping up
There are a quite a few ways to get up and running with Node.js on your Ubuntu 18.04 server. Your circumstances will dictate which of the above methods is best for your needs. While using the packaged version in Ubuntu's repository is the easiest method, using nvm offers additional flexibility.

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