mkdir "${HOME}/.npm-packages"
prefix=${HOME}/.npm-packages
NPM_PACKAGES="${HOME}/.npm-packages"
PATH="$NPM_PACKAGES/bin:$PATH"
# Unset manpath so we can inherit from /etc/manpath via the `manpath` command
unset MANPATH # delete if you already modified MANPATH elsewhere in your config
export MANPATH="$NPM_PACKAGES/share/man:$(manpath)"
Summarized from here