Run jshint on the command line fast (with v8 engine)

jshint-v8 is a modern and extreamly fast runner for the popular jshint JavaScript style checker. jshint is a fork of jslint implemented by the JavaScript guru Douglas Crockford in JavaScript itself.

Credits

• this work was forked from geekQ's github
• this work was inspired by jsbeautify implementation.
• original jslint-v8 implementation by jlbfalcao
• vim support and Rakefile by Vladimir Dobriakov AKA geekQ

Build

this on OSX (10.7.0) but if you have the prerequisites installed it should work fine on BSD and Linux as well.

Assumption You have python setup already with virtualenv

Setup V8

There are acouple steps to set up V8

Create a virtualenv:

$ cd /usr/local/dev
$ virtualenv v8-env --no-site-packages --distribute
$ source v8-env/bin/activate

Install scons:

$ easy_install scons

Get and build V8:

$ svn checkout http://v8.googlecode.com/svn/trunk/ v8-read-only
$ cd v8-read-only
$ scons snapshot=on library=shared arch=x64 d8

Warning

with OSX 10.7 Lion scons fails with ImportError: No module named SCons.Script so you need to export SCONS_LIB_DIR=/usr/local/src/v8-env/lib/python2.7/site-packages/scons-2.1.0-py2.7.egg/scons-2.1.0 to make it work

That was easy no? snapshot=on reportedly make it load faster. arch=x64 targets 64 architecture and d8 tells it to build the developer shell in release mode. Let's test it:

$ echo 'print("Hello, world!");' > test.js
$ ./d8 test.js
Hello World!!

If it prints Hello world!! it worked. So let's put it someplace permanent:

$ sudo cp d8 /usr/local/bin/
$ sudo cp libv8* /usr/local/lib/
$ cp include/* /usr/local/include/

Build jshint-v8

Python

$ sh build.sh

Ruby

$ V8_BASEDIR=/usr/local rake compile

If you do not have ruby/rake you can run g++ directly, please look inside Rakefile.

ruby convert_to_h.rb print_human.js > print_human. ruby convert_to_h.rb print_human.js > print_human.h ruby convert_to_h.rb print_vim.js > print_vim.h V8_BASEDIR=/usr/local/ rake compile

Run on console

$ jshint --browser file.js $ jshint --node file.js

checks the style for file.js. You can provide all the known jslint switches on the command line. Here --browser indicates that e.g. XMLHttpRequest object should be allowed and --node indicates Assume node.

Emacs

Create a flymake-jslint.el file

Create flymake-jslint.el in your emacs site direcory or somewher eon your load path with the folllowing contents:

(require 'flymake)

(defun flymake-jslint-init ()
  (let* ((temp-file (flymake-init-create-temp-buffer-copy
                     'flymake-create-temp-inplace))
         (local-file (file-relative-name
                      temp-file
                      (file-name-directory buffer-file-name))))
    (list "/usr/local/bin/jslint" (list local-file))))

(setq flymake-allowed-file-name-masks
      (cons '(".+\\.js$"
              flymake-jslint-init
              flymake-simple-cleanup
              flymake-get-real-file-name)
            flymake-allowed-file-name-masks))

(setq flymake-err-line-patterns
      (cons '("^Lint at line \\([[:digit:]]+\\) character \\([[:digit:]]+\\): \\(.+\\)$"
              nil 1 2 3)
            flymake-err-line-patterns))

(provide 'flymake-jslint)

Import it in your .emacs

Add the following to .emacs:

(require 'flymake-jslint)
(add-hook 'javascript-mode-hook
          (lambda () (flymake-mode 1)))

Run from vim

Set up jshint as make program in .vimrc:

autocmd BufRead,BufNewFile .js,.json setlocal makeprg=jslint--vim%

--vim provides error message formatting suitable for parsing in vim.

Now you can check your JavaScript easily with :make or even automatically on every file save or load.

See a screenshot for usage inside vim.