How can I use tsserver locally from node_modules?

[noghartt]

I'm a beginner with Emacs and I just try to use eglot as my LSP client. Following this setup I can run eglot, but I have a doubt now:

Is there a way to put eglot to run with tsserver from node_modules of my project instead of PATH? Because exists a tsserver on node_modules/.bin and I would like to use it.

[joaotavora]

I'd try C-u M-x eglot and figure out the relative path (which I think is relative to the project's path) to the server and entering manually at the prompt.

Then after you're happy and verify the server works, you modify the Elisp variable eglot-server-programs, either locally, or buffer-locally, or dir-locally to contain the very same string that you entered manually in the step before.

Thereafter a simple M-x eglot (no C-u) in one of your project's buffers will (hopefully) do the right thing.

If this answer is too terse, let's hope someone else chimes in, I don't have time to expand on it.

[zhaozhemin]

You can use add-node-modules-path. It will automatically add node_modules/.bin/ to your PATH.

[klandergren]

@noghartt my understanding is that, confusingly, tsserver is a "language server" but it does not currently implement Language Server Protocol (LSP) support to work with eglot. See tsserver should implement the Language Server Protocol #39459 for more information.

typescript-language-server, which is not an official TypeScript project but does wrap tsserver, is available for use with LSP clients like eglot.

Also, following @zhaozhemin's advice to use add-node-modules-path should work so that eglot can find typescript-language-server.

Here is an extract of my configuration that assumes you:

• have installed typescript-language-server in your project via your JavaScript package manager of choice (e.g. npm install typescript-language-server)
• are running emacs 29
• have the corresponding Emacs packages installed (if not, try M-x package-install)
• have add-node-modules-path in a directory lisp/ relative from your Emacs configuration directory

(use-package eglot
  :defer t)
  
(use-package add-node-modules-path
  :defer t

  :commands
  (add-node-modules-path)

  :load-path "lisp/")
  
(use-package typescript-ts-mode
  :defer t

  :mode
  ("\\.ts\\'" . typescript-ts-mode)     ; from `typescript-ts-mode.el`
  ("\\.tsx\\'" . tsx-ts-mode)           ; from `typescript-ts-mode.el`

  :config
  (progn
    (defun kl/ts-ts-mode-hook ()
      (add-node-modules-path)
      (eglot-ensure))

    (add-hook 'typescript-ts-mode-hook #'kl/ts-ts-mode-hook)
    (add-hook 'tsx-ts-mode-hook #'kl/ts-ts-mode-hook)))

You may need to tweak things to get it working for your set up. Good luck!