robert-dale-schell / tern

A JavaScript code analyzer for deep, cross-editor language support

Tern

This is Tern. Tern is a stand-alone, editor-independant JavaScript analyzer that can be used to improve the JavaScript integration of existing editors. It currently comes only with an online demo, but I am hard at work on Emacs and Vim plug-ins.

Thanks to a group of generous crowd funders, Tern is open-source software, under an MIT license.

Setting up the Emacs mode

(Disclaimer: This is a work in progress. The interface will change, and it has bugs. But it just might occasionally work.)

1. Make sure you are using Emacs 24 or later. The Tern mode requires lexical scoping.

2. Clone this repository somewhere. Do npm install to get the dependencies.

3. Make Emacs aware of emacs/tern.el. For example by adding this to your .emacs file:

   (add-to-list 'load-path "/path/to/tern/emacs/")
   (autoload 'tern-mode "tern.el" nil t)
   

4. Optionally set tern-mode to be automatically enabled for your JavaScript mode of choice. Here's the snippet for js-mode:

   (add-hook 'js-mode-hook (lambda () (tern-mode t)))
   

Buffers in tern-mode add a completion-at-point function that activates Tern's completion. So, unless you rebound the command, M-tab will trigger completion.

When the point is in an argument list, Tern will show argument names and types at the bottom of the screen.

The following keys are bound:

• M-. to jump to the definition of the thing under the cursor.
• M-, brings you back to last place you were when you pressed M-..
• C-c C-r to rename the variable under the cursor.