Automatically quit vim if NERDTree is last and only buffer

A script to do exactly this has been posted on the NERDTree issue list. Checkout issue-21 on GitHub for nerdtree.

This leads to the single line command for your vimrc here:

autocmd bufenter * if (winnr("$") == 1 && exists("b:NERDTree") && b:NERDTree.isTabTree()) | q | endif

function! s:CloseIfOnlyControlWinLeft()
  if winnr("$") != 1
    return
  endif
  if (exists("t:NERDTreeBufName") && bufwinnr(t:NERDTreeBufName) != -1)
        \ || &buftype == 'quickfix'
    q
  endif
endfunction
augroup CloseIfOnlyControlWinLeft
  au!
  au BufEnter * call s:CloseIfOnlyControlWinLeft()
augroup END

From my vimrc, based on a version from janus repo.

Enhancements: also close if only a quickfix window is left. It uses the BufEnter autocommand instead, which is required for &bt to work properly.