Note, how to install io.js and node alongside. It also covers, how to install global npm modules, without changing the ownership of /usr/local

install.md

Install node.js & io.js using nvm

• Read about nvm https://github.com/creationix/nvm

brew install nvm
nvm install iojs

# .zshrc
export NVM_DIR=$(brew --prefix)/var/nvm
source $(brew --prefix nvm)/nvm.sh

# Now iojs -v, node-v should print the latest iojs version

Install npm global packages without root permissions

npm config set prefix ~/npm

# .zshrc
export PATH="$PATH:$HOME/npm/bin"