Upgrade Node.js to the latest version on Mac OS

Here's how I successfully upgraded from v0.8.18 to v0.10.20 without any other requirements like brew etc, (type these commands in the terminal):

1. sudo npm cache clean -f (force) clear you npm cache
2. sudo npm install -g n install n (this might take a while)
3. sudo n stable upgrade to the current stable version

Note that sudo might prompt your password.

Additional note regarding step 3: stable can be exchanged for latest, lts (long term support) or any specific version number such as 0.10.20.

If the version number doesn't show up when typing node -v, you might have to reboot.

These instructions are found here as well: davidwalsh.name/upgrade-nodejs
More info about the n package found here: npmjs.com/package/n
More info about Node.js' release schedule: github.com/nodejs/Release

If you initially installed Node.js with Homebrew, run:

brew update
brew upgrade node
npm install -g npm

Or as a one-liner:

brew update && brew upgrade node && npm install -g npm

A convenient way to change versions is to use nvm:

brew install nvm

To install the latest version of Node.js with nvm:

nvm install node

If you installed via a package, then download the latest version from nodejs.org. See Installing Node.js and updating npm.

Because this seems to be at the top of Google when searching for how to upgrade nodejs on mac I will offer my tip for anyone coming along in the future despite its age.

Upgrading via NPM
You can use the method described by @Mathias above or choose the following simpler method via the terminal.

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

After which you may opt to confirm the upgrade

node -v

Your nodejs should have upgraded to the latest version. If you wish to upgrade to a specific one say v0.8.19 then instead of

sudo n stable

use

sudo n 0.8.19

EDIT Avoid using sudo unless you need to. Refer to comment by Steve in the comments