Douglas Crockford’s JSLint script is almost a golden standard when it comes to checking the syntax and general sanity of your javascript files. Being lazy by nature, I got tired of copying and pasting my code into the web form.

I wanted to be able to run the JSLint tool from the command line. JSLint itself is written in javascript. It’s a 6000-line beast. How do you run a javascript library as a command line utility? The answer is node.js.

I wrote a quick little script that takes a single argument (your file) and runs JSLint over it, printing any errors to the console. I call it jslintnode.js and the code is on Github.

Well, checking my files from the command line is certainly better than using the web interface. But I still have to run it over and over. As you may know, I’m fanatical vim user. There is a cool plugin called syntastic which runs through the file you are editing each time you save it. It puts little >>> characters next to the line you are editing which tells you that you screwed up and need to fix that line.

However, by default, syntastic uses the jsl utility to check javascript files. With a little bit of work, you can modify the original script to use our jslintnode.js utility.

Go into the /syntax_checkers/ directory and open up the javascript.vim file.

Change this line:

if !executable('jsl')

to this:

if !executable('jslintnode.js')

And replace the body of the SyntaxCheckers_javascript_GetLocList() function with the following:

let makeprg = "jslintnode.js ".shellescape(expand('%'))
let errorformat='%W%f(%l): lint warning: %m,%-Z%p^,%W%f(%l): warning: %m,%-Z%p^,%E%f(%l): SyntaxError: %m,%-Z%p^,%-G'
return SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })

Save and restart vim.

That’s it. Now as you’re editing any javascript files you will get instant feedback as to the quality of your code as judged by JSLint. And remember that JSLint will hurt your feelings.