vim/ftplugin/json.vim
setlocal expandtab " Use spaces.
setlocal shiftwidth=2
let g:neoformat_json_prettier = {
\ 'exe': 'prettier',
\ 'args': ['--stdin', '--parser', 'json'],
\ 'stdin': 1,
\ }
nnoremap <Leader>y :Neoformat prettier<CR>
augroup json_group
autocmd!
autocmd BufWritePre * Neoformat prettier
augroup END