How to config npm to install with global option (-g) into home dir

.bashrc

# ....
# ...
### First in the terminal ###
# $ NPM_PACKAGES="$HOME/.npm-packages"
# $ mkdir -p "$NPM_PACKAGES"
# $ echo "prefix = $NPM_PACKAGES" >> ~/.npmrc
### End ###

#######################
### In .bashrc file ###
#######################

# NPM packages in home directory
NPM_PACKAGES="$HOME/.npm-packages"

# Tell our environment about user-installed node tools
PATH="$NPM_PACKAGES/bin:$PATH"
# Unset manpath so we can inherit from /etc/manpath via the `manpath` command
unset MANPATH  # delete if you already modified MANPATH elsewhere in your configuration
MANPATH="$NPM_PACKAGES/share/man:$(manpath)"

# Tell Node about these packages
NODE_PATH="$NPM_PACKAGES/lib/node_modules:$NODE_PATH"

### Terminal ###
# $ source ~/.bashrc
# $ npm install -g <package>
### End ###

# source: http://stackoverflow.com/questions/10081293/install-npm-into-home-directory-with-distribution-nodejs-package-ubuntu/13021677