add lsp support to js-mode (#1748)

extensions/js-mode/lem-js-mode.asd

@@ -3,4 +3,6 @@
                "lem-xml-mode")
   :serial t
   :components ((:file "js-mode")
-               (:file "eslint")))
+               (:file "eslint")
+               (:file "lsp-config")))
+

extensions/js-mode/lsp-config.lisp

@@ -0,0 +1,12 @@
+(uiop:define-package #:lem-js-mode/lsp-config
+  (:use #:cl)
+  (:export))
+(in-package :lem-js-mode/lsp-config)
+
+(lem-lsp-mode:define-language-spec (js-spec lem-js-mode:js-mode)
+  :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)