toggle coc-deno and coc-tsserver extensions based on ecma runtime

.vimrc

@@ -124,7 +124,36 @@ function! s:disable_coc_for_type()
     let b:coc_enabled = 0
   endif
 endfunction
+function! s:enable_extensions_for_deno()
+  call CocActionAsync('activeExtension', 'coc-deno')
+  call CocActionAsync('deactivateExtension', 'coc-tsserver')
+endfunction
+function! s:enable_extensions_for_node()
+  call CocActionAsync('activeExtension', 'coc-tsserver')
+  call CocActionAsync('deactivateExtension', 'coc-deno')
+endfunction
+function! s:set_ts_lsp()
+  " enable/disable coc-tsserver/coc-deno based on detection of diff ecma runtimes
+  let l:bufname = expand('%')
+  " The buffer is deno lsp virtual file
+  if l:bufname =~# '^deno:/'
+    call s:enable_extensions_for_deno()
+    return
+  endif
+  let l:path = empty(l:bufname) ? '.' : expand('%:p:h')
+  if !empty(finddir('node_modules', l:path . ';')) || !empty(findfile('package.json', l:path . ';'))
+    call s:enable_extensions_for_node()
+    return
+  endif
+  if !empty(findfile('deno.jsonc', l:path . ';')) || !empty(findfile('import_map.json', l:path . ';'))
+    call s:enable_extensions_for_deno()
+    return
+  endif
+  " TODO: check for existence of .vim/coc-settings.json and look for
+  " deno.enable and/or tsserver.enable config props
+endfunction
 autocmd BufRead,BufNewFile * call s:disable_coc_for_type()
+autocmd filetype javascript,typescript call s:set_ts_lsp()
 " Tweaking colours used in vim w/ coc.nvim
 highlight Conceal ctermfg=7 ctermbg=0