Complete installation instructions have since been uploaded here by Nodesource. It is copied below for your reference. Instructions are the same for updating to the latest version.

Node.js v10.x:

NOTE: If you are using Ubuntu Precise or Debian Wheezy, you might want to read about running Node.js >= 6.x on older distros

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_10.x | bash -

apt-get install -y nodejs

Node.js v9.x:

NOTE: If you are using Ubuntu Precise or Debian Wheezy, you might want to read about running Node.js >= 6.x on older distros

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_9.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_9.x | bash -

apt-get install -y nodejs

Node.js v8.x:

NOTE: If you are using Ubuntu Precise or Debian Wheezy, you might want to read about running Node.js >= 6.x on older distros

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_8.x | bash -

apt-get install -y nodejs

Node.js v7.x:

NOTE: Debian Wheezy and Ubuntu Precise packages are NOT available for this release. Please reference running Node.js >= 4.x on older distros

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_7.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_7.x | bash -

apt-get install -y nodejs

Node.js v6.x:

NOTE: If you are using Ubuntu Precise or Debian Wheezy, you might want to read about running Node.js >= 4.x on older distros.

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_6.x | bash -

apt-get install -y nodejs

Node.js v5.x:

NOTE: If you are using Ubuntu Precise or Debian Wheezy, you might want to read about running Node.js >= 4.x on older distros.

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_5.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_5.x | bash -

apt-get install -y nodejs

Node.js v4.x:

NOTE: If you are using Ubuntu Precise or Debian Wheezy, you might want to read about running Node.js >= 4.x on older distros.

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_4.x | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_4.x | bash -

apt-get install -y nodejs

Node.js v0.12:

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_0.12 | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_0.12 | bash -

apt-get install -y nodejs

Node.js v0.10:

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_0.10 | sudo -E bash -

sudo apt-get install -y nodejs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_0.10 | bash -

apt-get install -y nodejs

io.js v3.x:

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_iojs_3.x | sudo -E bash -

sudo apt-get install -y iojs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_iojs_3.x | bash -

apt-get install -y iojs

io.js v2.x:

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_iojs_2.x | sudo -E bash -

sudo apt-get install -y iojs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_iojs_2.x | bash -

apt-get install -y iojs

io.js v1.x:

Note: this branch of io.js is not actively maintained and is not recommended for production use.

# Using Ubuntu

curl -sL https://deb.nodesource.com/setup_iojs_1.x | sudo -E bash -

sudo apt-get install -y iojs



# Using Debian, as root

curl -sL https://deb.nodesource.com/setup_iojs_1.x | bash -

apt-get install -y iojs

This PPA is out of date and not maintained anymore; you should consider other answers instead of this one.

You can install the latest version from PPA:

sudo add-apt-repository ppa:chris-lea/node.js  

sudo apt-get update  

sudo apt-get install nodejs

I use NVM to handle my Node versions. Very simple to set up and easy to use.

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.0/install.sh | bash

export NVM_DIR="$HOME/.nvm"

[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" # This loads nvm

To install NVM globally instead, use the following curl command instead of the one above (and presumably don't use the second command but do use the third one)

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.0/install.sh | NVM_DIR=/usr/local/nvm bash

Then use nvm install stable (or insert a version number instead of stable) to get the latest/a specific version of Node. Use nvm use stable (or a specific version number) to use that Node version. Use nvm ls to see what Node versions you have installed and nvm uninstall stable(or a specific version number) to remove a specific version of Node.

Sources:
Install, usage

I also recommend using nvm instead, and also removing the already installed version to avoid conflicts in the terminal

sudo apt purge nodejs npm

then install nvm and use it

Video Explanation

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash

to download and install nvm

nvm install node

should download and install the latest version of node.

To update node later on just do

nvm install node

nvm alias default node

I tried the same list commands on my ubuntu 14.04 but it was still throwing an error.

Commands I executed were:

sudo add-apt-repository ppa:chris-lea/node.js  

sudo apt-get update  

sudo apt-get install nodejs

and the error i was getting:

Invalid version 0.12.2

Line 299: curl not found in /bin/n

What I figured out was curl utility was not installed on my os.

I executed command:

apt-get install curl

(use sudo as prefix if you are not su)

and then repeated the steps suggest in answer and it work ;)

This one installs the latest node v0.12.* from nodesource.

sudo apt-get install -y curl

curl -sL https://deb.nodesource.com/setup_0.12 | sudo bash -

sudo apt-get install -y nodejs

For node v4.x

curl -sL https://deb.nodesource.com/setup_4.x | sudo -E bash -

sudo apt-get install -y nodejs

I suggest you first remove all nodejs installs
then execute below script once you edit with desired nodejs version and its install parent directory

see all available nodejs versions

https://nodejs.org/dist/

below script will allow you to install any of those nodejs versions on linux or OSX

#!/bin/bash



#     usage :

#

#     edit two vars in below :  NODE_VER  and  CODE_PARENT_DIR

#

# ... execute this script as yourself unless you choose a root owned value for var CODE_PARENT_DIR

#     whichever id you execute this as determines the id you will issue npm commands as :  npm install -g foo-bar

#

#     NOTE - nodejs comes bundled with npm ... so no need to do separate npm install

#            this scripts runs fine on linux or OSX



# ...  copy all the lines starting here  .. top of copy  ....   and ending ... end of copy  ...

#      and paste into your ~/.bashrc file so proper env vars get set 



# ............... top of copy  ........................  install_node.sh



# export NODE_VER=v7.2.0  # see available versions at https://nodejs.org/dist/

# export NODE_VER=v8.5.0  # edit this line next time you need to update nodejs  

export NODE_VER=v9.3.0  # edit this line next time you need to update nodejs



# ...  pick parent dir of nodejs install  ... comment out or remove ONE of below

# export CODE_PARENT_DIR=/opt/code  # root owned dir ... requires you to sudo prior to npm install going forward

export CODE_PARENT_DIR=${HOME}    # RECOMMENDED execute as yourself including npm install



# ......... following env vars are OK no edits needed ... only ever need to edit above vars



curr_OS=$( uname )



echo curr_OS $curr_OS



if [[ "${curr_OS}" == "Darwin" ]]; then



    OS_ARCH=darwin-x64



elif [[ "${curr_OS}" == "Linux" ]]; then



    OS_ARCH=linux-x64

else

    echo "ERROR - failed to recognize OS $curr_OS"

    exit 5

fi



if [[ -z ${CODE_PARENT_DIR} ]]; then



    echo "ERROR - failed to see env var CODE_PARENT_DIR"

    exit 5

fi



export NODE_CODEDIR=${CODE_PARENT_DIR}/nodejs

export COMSUFFIX=tar.gz

export NODE_NAME=node-${NODE_VER}

export NODE_PARENT=${NODE_CODEDIR}/${NODE_NAME}-${OS_ARCH} 



export PATH=${NODE_PARENT}/bin:${PATH}

export NODE_PATH=${NODE_PARENT}/lib/node_modules



# ............... end of copy  ........................  install_node.sh



# copy and paste above from ... top of copy ... to here into your file ~/.bashrc   



echo

echo "NODE_CODEDIR $NODE_CODEDIR<--"

echo



echo "mkdir -p ${NODE_CODEDIR}"

echo

      mkdir -p ${NODE_CODEDIR}

echo



echo "cd ${NODE_CODEDIR}"

      cd ${NODE_CODEDIR}

echo



# this is compiled code NOT source



[ -f ${NODE_NAME}-${OS_ARCH}.${COMSUFFIX} ] && rm ${NODE_NAME}-${OS_ARCH}.${COMSUFFIX} # if file exists remove



echo "wget -q --show-progress https://nodejs.org/download/release/${NODE_VER}/${NODE_NAME}-${OS_ARCH}.${COMSUFFIX}"

      wget -q --show-progress https://nodejs.org/download/release/${NODE_VER}/${NODE_NAME}-${OS_ARCH}.${COMSUFFIX}

echo



echo "tar -C ${NODE_CODEDIR} -xf ${NODE_NAME}-${OS_ARCH}.${COMSUFFIX}"

      tar -C ${NODE_CODEDIR} -xf ${NODE_NAME}-${OS_ARCH}.${COMSUFFIX}

echo



[ -f ${NODE_NAME}-${OS_ARCH}.${COMSUFFIX} ] && rm ${NODE_NAME}-${OS_ARCH}.${COMSUFFIX} # if file exists remove



# ...........  done ........... #



which node



node --version



# ....  bottom of file   install_node.sh

If using n does not work, you can install the latest version of nodejs (i. e. version 8) running the following commands:

curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -



sudo apt-get install -y nodejs

Further instructions are here.

NVM (Node Version manager) with --lts

NVM was mentioned at: https://askubuntu.com/a/441527/52975 but here goes a more complete usage example, including the sane --lts version.

NVM installs both the latest stable node and npm for you

curl https://raw.githubusercontent.com/creationix/nvm/master/install.sh | sh

source ~/.nvm/nvm.sh

nvm install --lts

nvm use --lts

npm --version

Now test it out with a dummy package:

npm install --global vaca

vaca

Since the sourcing has to be done for every new shell, you will probably want to add the following to your .bashrc:

f="$HOME/.nvm/nvm.sh"

if [ -r "$f" ]; then

  . "$f" &>'/dev/null'

  nvm use --lts &>'/dev/null'

fi

Advantages:

• allows you to use multiple versions of Node and without sudo




• is analogous to Ruby RVM and Python Virtualenv, widely considered best practice in Ruby and Python communities




• downloads a pre-compiled binary where possible, and if not it downloads the source and compiles one for you

We can easily switch node versions with:

nvm install 0.9.0

nvm install 0.9.9

nvm use 0.9.0

node --version

#v0.9.0

nvm use 0.9.9

node --version

#v0.9.9

You can then use a git tracked .nvmrc file to indicate the node version required for a given project: https://stackoverflow.com/questions/24869959/how-do-i-specify-a-local-version-of-node-for-a-project/54503474#54503474

Tested in Ubuntu 17.10.

If you are behind a proxy, maybe you could get this error when you run 'sudo n stable':

Error: invalid version

You have to set the env variables like this:

export HTTP_PROXY=http://your-proxy-url:port

export HTTPS_PROXY=http://your-proxy-url:port

And then run the command passing these variables to the root user:

sudo -E n stable

Using nvm is preferred method. First install nvm:

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash

Then install nodejs:

nvm install node

Now on, you can easy switch versions of node.