Fish shell function that returns the current node version if you're using nvm

fish_get_node_version.fish

function __use_node_version
  # test if .nvmrc exists
  if test -e .nvmrc
    # test if variable exist and compare version with .nvmrc
    if test \( -n "$NVMRC_CURRENT" \) -a \( $NVMRC_CURRENT = (cat .nvmrc) \) > /dev/null 2>&1
      # node version allready set
    else
      # create a nvm current variable
      set -g NVMRC_CURRENT (cat .nvmrc)
      nvm use $NVMRC_CURRENT > /dev/null
      #echo 'set node version'
    end  
  end
end

function __node_version
  if type "nvm" > /dev/null 2>&1
    __use_node_version
    set node_version (nvm current)
  else
    set node_version "system"
  end

  echo -n (set_color green) ⬢ ‹$node_version› (set_color normal)
end

# it can then be used in the prompt function
function fish_prompt
  # ...
  __node_version
  # ...
end