how to install npm after purge

Question

As I need an updated version of NodeJS, I first remove old version... By:

 apt-get remove --purge nodejs
 apt-get remove --purge node
 apt-get autoremove

... after sucess on install last version of NodeJS, I ran the npm install procedure,

 node --version  # now is ok!
 sudo apt-get install npm  # ERROR!!!!

So, how to install npm in this context (after this purge process)

EDIT:

PS: as I show by link above and inline-comment above, nodejs --version is OK, is good, no problem. This question was about npm and apt-get... And now I see that part of the answer is here.

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The error messages, same as this similar question

The following packages have unmet dependencies:
 npm : Depends: nodejs but it is not going to be installed
       Depends: node-abbrev (>= 1.0.4) 
       Depends: nodejs-dev
       ...
       Depends: ... but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Answer 1

... Nobody say, but the problem is not with my NodeJS or my UBUNTU, the problem is like a bug with sudo apt-get install npm, this command is with a bug: need to fix the message.

As sayd here in similar question, the npm was installed by the modern NodeJS's installation (!!), so apt-get must say "ok, no problem, you have a good and updated npm".

Conclusion:

1. use only "curl + apt" commands with the correct setup_N.x choice, as illustred in all links posted here. The installation of nodejs will install also npm.

2. not use apt-get install npm, avoid it. Is a bug.

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NOTE: a typical "curl + apt" is

 curl -sL https://deb.nodesource.com/setup_5.x | sudo -E bash -
 sudo apt-get install -y nodejs

and, after sucess with this install procedure, to check npm existence, use

  npm --version

so, if shows a version number (like 3.3.12), npm was installed!

IMPORTANT: to update npm (ex. from 3.3.12 to 3.5.2) not use apt-get (!), use the npm itself,

 sudo npm install npm -g

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EDIT 2017

Today, 2017, at UBUNTU 16 LTS, is possible... And using only atp (is most friendly tham apt-get):

sudo apt update
sudo apt install nodejs  # need it first!
sudo apt install npm

... But ...it is the "most updated version of the sluggish LTS", ... check each version (!)...

Step-by-step for a specific version choice (v6.x as illustration), as this tutorial:

1. curl -sL https://deb.nodesource.com/setup_6.x -o nodesource_setup.sh

2. sudo bash nodesource_setup.sh

3. atp install nodejs

Answer 2

Remove nodejs and fix broken packages.

sudo apt-get --purge remove nodejs node npm
sudo apt-get clean
sudo apt-get autoclean
sudo apt-get -f install
sudo apt-get autoremove

Install nodejs using a PPA

curl -sL https://deb.nodesource.com/setup_4.x | sudo -E bash -
sudo apt-get install -y nodejs

Create a symbolic link for node, as many Node.js tools use this name to execute.

sudo ln -s /usr/bin/nodejs /usr/bin/node

To compile and install native addons from npm you may also need to install build tools:

sudo apt-get install -y build-essential