Switch Node.js version with Homebrew

use-node.sh

# Assumes you have installed individual major versions with Homebrew, like node@8,
# this command allows you to switch by calling e.g. `use-node 8`, or to get the
# current latest version (`brew install node`) if you don't pass an argument.
# Notice: Since it modifies the env, this will only work for the current session.
# I.e. other terminal windows will have the default Node version, unless they’re also changed.
use-node() {
  wanted=$([ "$1" == "" ] && echo "node" || echo "node@$1")
  prefix=$(brew --prefix $wanted 2> /dev/null)
  if [ "$prefix" != "" ]; then
    PATH="$(echo $PATH | tr ':' '\n' | grep -v ${prefix%@*} | tr '\n' ':')"
    if [ "$1" != "" ]; then PATH="$prefix/bin:$PATH"; fi
    export PATH
  else
    echo "Node version '$1' not available"
  fi
}

Auto-use a specified version when changing dir; put the following in your .profile or .bashrc:

cd() {
  builtin cd "$@" || return

  if [ -f ".node-version" ]; then
    use-node $(cat .node-version)
  fi
}