nvim/nvim-config/coc.vim

" Thanks https://www.chrisatmachine.com/Neovim/17-snippets/
" Use <C-l> for trigger snippet expand.
imap <C-l> <Plug>(coc-snippets-expand)

" Use <C-j> for select text for visual placeholder of snippet.
vmap <C-j> <Plug>(coc-snippets-select)

" Use <C-j> for jump to next placeholder, it's default of coc.nvim
let g:coc_snippet_next = '<c-j>'

" Use <C-k> for jump to previous placeholder, it's default of coc.nvim
let g:coc_snippet_prev = '<c-k>'

" Use <C-j> for both expand and jump (make expand higher priority.)
imap <C-j> <Plug>(coc-snippets-expand-jump)

" Use `[g` and `]g` to navigate diagnostics
" Use `:CocDiagnostics` to get all diagnostics of current buffer in location list.
nmap <silent> [g <Plug>(coc-diagnostic-prev)
nmap <silent> ]g <Plug>(coc-diagnostic-next)

" GoTo code navigation.
nmap <silent> gd <Plug>(coc-definition)
nmap <silent> gy <Plug>(coc-type-definition)
nmap <silent> gi <Plug>(coc-implementation)
nmap <silent> gr <Plug>(coc-references)

inoremap <silent><expr> <Tab>

" Use K to show documentation in preview window.
nnoremap <silent> K :call <SID>show_documentation()<CR>

function! s:show_documentation()
  if CocAction('hasProvider', 'hover')
    call CocActionAsync('doHover')
  else
    call feedkeys('K', 'in')
  endif
endfunction

" MDX
" Thanks https://github.com/neoclide/coc-prettier/issues/127#issuecomment-850598753
let g:coc_filetype_map = { 'markdown.mdx': 'mdx' }

" use <tab> for trigger completion and navigate to the next complete item
function! s:check_back_space() abort
  let col = col('.') - 1
  return !col || getline('.')[col - 1]  =~ '\s'
endfunction

" Use tab for trigger completion with characters ahead and navigate.
" NOTE: Use command ':verbose imap <tab>' to make sure tab is not mapped by
" other plugin before putting this into your config.
inoremap <silent><expr> <TAB>
      \ pumvisible() ? "\<C-n>" :
      \ <SID>check_back_space() ? "\<TAB>" :
      \ coc#refresh()
inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<C-h>"