How can I update NodeJS and NPM to the next versions?

See the docs for the update command:

npm update [-g] [<pkg>...]

This command will update all the packages listed to the latest version (specified by the tag config), respecting semver.

Additionally, see the documentation on Node.js and NPM installation and Upgrading NPM.

The following original answer is from the old FAQ that no longer exists, but should work for Linux and Mac:

How do I update npm?

npm install -g npm

Please note that this command will remove your current version of npm. Make sure to use sudo npm install -g npm if on a Mac.

You can also update all outdated local packages by doing npm update without any arguments, or global packages by doing npm update -g.

Occasionally, the version of npm will progress such that the current version cannot be properly installed with the version that you have installed already. (Consider, if there is ever a bug in the update command.) In those cases, you can do this:

curl https://www.npmjs.com/install.sh | sh

To update Node.js itself, I recommend you use nvm, the Node Version Manager.

I found this really neat way of updating node on David Walsh's blog, you can do it by installing n:

sudo npm cache clean -fsudo npm install -g nsudo n stable

It will install the current stable version of node.

EDIT: Please don't use n anymore. I recommend using nvm. You can simply install stable by following the commands below:

nvm ls-remotenvm install <version> nvm use <version>

Updating npm is easy:

npm install npm@latest -g