run `nvm use` automatically every time there's a .nvmrc file on the directory

How to configure my shell so that nvm use run automatically every time there's a .nvmrc file on the directory and use the latest version or a global config when there's no .nvmrc file?

If you use zsh (z shell):

Calling 'nvm use' automatically in a directory with a .nvmrc file

Put this into your $HOME/.zshrc to call nvm use automatically whenever you enter a directory that contains an .nvmrc file with a string telling nvm which node to use:

# place this after nvm initialization!
autoload -U add-zsh-hook
load-nvmrc() {
  local node_version="$(nvm version)"
  local nvmrc_path="$(nvm_find_nvmrc)"

  if [ -n "$nvmrc_path" ]; then
    local nvmrc_node_version=$(nvm version "$(cat "${nvmrc_path}")")

    if [ "$nvmrc_node_version" = "N/A" ]; then
      nvm install
    elif [ "$nvmrc_node_version" != "$node_version" ]; then
      nvm use
    fi
  elif [ "$node_version" != "$(nvm version default)" ]; then
    echo "Reverting to nvm default version"
    nvm use default
  fi
}
add-zsh-hook chpwd load-nvmrc
load-nvmrc

More info: https://github.com/creationix/nvm#zsh

If you use bash you can add this to your ~/.bashrc file:

enter_directory() {
  if [[ $PWD == $PREV_PWD ]]; then
    return
  fi

  PREV_PWD=$PWD
  [[ -f ".nvmrc" ]] && nvm use
}

export PROMPT_COMMAND=enter_directory

Excellent answer from @devius.

I just extended it so it can revert to the default version when leaving a directory with .nvmrc to another without it.

~/.bashrc:

#
# Run 'nvm use' automatically every time there's 
# a .nvmrc file in the directory. Also, revert to default 
# version when entering a directory without .nvmrc
#
enter_directory() {
if [[ $PWD == $PREV_PWD ]]; then
    return
fi

PREV_PWD=$PWD
if [[ -f ".nvmrc" ]]; then
    nvm use
    NVM_DIRTY=true
elif [[ $NVM_DIRTY = true ]]; then
    nvm use default
    NVM_DIRTY=false
fi
}

export PROMPT_COMMAND=enter_directory

Following @doug-barbieri's suggestion, the script below will not change node back to the default version if there's no .nvmrc file in the current directory but there is one in the parent sub-directory.

~/.bashrc:

enter_directory() {
  if [[ $PWD == $PREV_PWD ]]; then
    return
  fi

  if [[ "$PWD" =~ "$PREV_PWD" && ! -f ".nvmrc" ]]; then
    return
  fi

  PREV_PWD=$PWD
  if [[ -f ".nvmrc" ]]; then
    nvm use
    NVM_DIRTY=true
  elif [[ $NVM_DIRTY = true ]]; then
    nvm use default
    NVM_DIRTY=false
  fi
}

The trick is here:

if [[ "$PWD" =~ "$PREV_PWD" && ! -f ".nvmrc" ]]; then
  return
fi

It checks if the PWD contains PREV_PWD. For example, if /home/user1/a/b contains /home/user1/a.

This can be extended to work with Starship (even on Git Bash for Windows not WSL) as well using the starship_precmd_user_func

set_win_title() {
  BASEPWD=$(basename "$PWD")
  echo -ne "\033]0; 📁 $BASEPWD \a" < /dev/null
  if [[ $PWD == $PREV_PWD ]]; then
    return
  fi

  if [[ "$PWD" =~ "$PREV_PWD" && ! -f ".nvmrc" ]]; then
    return
  fi

  PREV_PWD=$PWD
  if [[ -f ".nvmrc" ]]; then
    nvm use
    NVM_DIRTY=true
  elif [[ $NVM_DIRTY = true ]]; then
    nvm use default
    NVM_DIRTY=false
  fi
}
starship_precmd_user_func="set_win_title"
eval "$(starship init bash)"

I just found out about Automatic Version Switching for Node.js https://github.com/wbyoung/avn, you can use that.

You can also follow this thread https://github.com/creationix/nvm/issues/110

run `nvm use` automatically every time there's a .nvmrc file on the directory

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