I'm using autozimu/LanguageClient-neovim [1]
From my .config/nvim/init.vim:
call plug#begin('~/.local/share/nvim/plugged')
Plug 'autozimu/LanguageClient-neovim', { 'do': ':UpdateRemotePlugins' }
call plug#end()
let g:LanguageClient_serverCommands = {
\ 'javascript': ['node','/Users/jrousseau/javascript-typescript-langserver/lib/language-server-stdio.js'],
\ }
" Automatically start language servers.
let g:LanguageClient_autoStart = 1
[1] https://github.com/autozimu/LanguageClient-neovim