coc.nvim uses jsonc as configuration file format, the same as VSCode. It's json that supports comments, like:

{
  // my variable
  "key.sub-key": "value"
}

To get correct comment highlighting, make sure you use a recent Vim (8.2.3117 or later) or NeoVim (0.6.0 or later) version. Alternatively you can install vim-jsonc (which has built-in support for coc-settings.json), or even simply add:

  autocmd FileType json syntax match Comment +\/\/.\+$+

to your .vimrc or init.vim.

Use the command :CocConfig to open your user configuration file, you can create a shortcut for the command like this:

function! SetupCommandAbbrs(from, to)
  exec 'cnoreabbrev <expr> '.a:from
        \ .' ((getcmdtype() ==# ":" && getcmdline() ==# "'.a:from.'")'
        \ .'? ("'.a:to.'") : ("'.a:from.'"))'
endfunction
" Use C to open coc config
call SetupCommandAbbrs('C', 'CocConfig')

Variables would be expanded in string values of configuration, supported variables:

• ${userHome} the path of the user's home folder
• ${cwd} current working directory of vim

some additional variables see:

:h coc-configuration-expand

• LSP uses JSON for language server configuration.
• Extensions can contribute JSON schema for json validation.
• coc-json can provide completion and validation for the settings file, which makes configuration much easier and more reliable.
• Most configurations take effect just after the settings file is saved, you don't need to restart vim or coc.

To enable intellisense for coc-settings.json, install the json language extension coc-json by:

:CocInstall coc-json

In your vim.

Checkout :h coc-config for all built in configurations.

Just like VSCode, each coc.nvim extension can contribute configuration sections, for example:

• coc-tsserver uses section tsserver, typescript and javascript
• coc-json uses section json

To get detailed options for existing configurations, just try the completion in the file coc-settings.json: