JavaScript
An example JS config for LSP:
(lem-lsp-mode/lsp-mode::define-language-spec
(js-spec lem-js-mode:js-mode)
;; thanks @sasanidas
:language-id "javascript"
:root-uri-patterns '("package.json" "tsconfig.json")
:command '("typescript-language-server" "--stdio")
:install-command "npm install -g typescript-language-server typescript"
:readme-url "https://github.com/typescript-language-server/typescript-language-server"
:connection-mode :stdio)