An attempt at context sensitive auto-completion for Javascript in Emacs using js2-mode's parser and Skewer-mode (requires Emacs 24.3). Inspired by the work of others on projects such as js2-mode, skewer-mode and js2-refactor I decided to add to the concept of Emacs as a Javascript IDE.

Here is a screenshot of the auto completion in action using the optional dependency, auto-complete-mode.

• Auto complete with js2-browser-externs
• Auto complete with js2-keywords
• Auto complete with js2-ecma-262-externs

Each of the above settings can be customized and are enabled by default.

• Partial support for completing properties
• Show function interface or initial value for object properties
• Support for external libraries

Ac-js2 uses skewer-mode to evaluate Javascript code in the browser which could have undesired side effects. Therefore these features are turned off by default, see Setup to enable these features anyway :).

• Navigation commands to jump to variables, functions and object properties.

i.e. Given the following proprety reference:

foo.bar.baz();

placing the cursor on foo, bar or baz and executing ac-js2-jump-to-definition or M-. will take you straight to their respective definitions. Executing M-, will jump you back to where you were.

• Completion of variable and function names in current scope
• Popup documentation for variables and function names in buffer

Experimental yansippet integration

Recently added ac-js2-expand-function that will expand a function's parameters bound to C-c C-c. Expansion will only work if the cursor is after the function.

Note: Navigation only works if the definition is in the same file.

Easiest way to get ac-js2 is to install it from MELPA. You may need this snippet

(add-to-list 'package-archives
              '("melpa" . "http://melpa.milkbox.net/packages/") t)

if you don't have it already to fetch packages from MELPA.

Enable ac-js2 in js2-mode as follows:

(add-hook 'js2-mode-hook 'ac-js2-mode)

• skewer-mode (MELPA)
• js2-mode (ELPA)

Auto-complete is no longer a dependency however ac-js2 will use it if you have it installed. The main reason for this is to allow users to use their preferred completion front end.

• auto-complete (ELPA)

For those of you who prefer Company mode, support is on its way.

Copy the snippet below if you want to evaluate your Javascript code for candidates. Not setting this value will still provide you with basic completion.

(setq ac-js2-evaluate-calls t)

Add any external Javascript files to the variable below. Make sure you have initialised ac-js2-evaluate-calls to t if you add any libraries.

(setq ac-js2-external-libraries '("full/path/to/a-library.js"))

Call run-skewer and open up a Javascript file. Type part of a variable and call completion-at-point or if you have auto-complete installed wait for the popup.

Note that any code you evaluate using Skewer may add completion candidates for the global object.