Javascript Linting…

Suffice to say, my minions write a quantity of Javascript. And testing it isn’t all that easy. While rummaging the internet, I came across @NeilCrosby‘s FrontEndTestSuite which aims to automate e.g. w3c validator checks and so on – there will be more on that later I suspect once I get it working.

Anyway, the first part I wanted to do is to run a Javascript linter on things…. as I haven’t really come across these before.

I’ve found two approaches :

Install JavascriptLint


Build instructions for the lazy – uncompress/extract the files from the archive, then :

  1. cd jsl-0.3.0/src
  2. make -f Makefile.ref
  3. cp Linux_All_DBG.OBJ/jsl /usr/local/bin

Usage looks a bit like :

jsl -process $file

As per the ‘help’ documentation, it returns different exit codes depending how things went (e.g. 0 – everything good; 1 – warnings etc).

Aside from the annoying compile step, this seemed the easiest to setup, and friendliest to use from the command line.

Mozilla’s Rhino & JSLint.js

This is the approach expected by Neil’s TestSuite above (more soon, perhaps).

Download the Mozilla Rhino thing – for me this is a simple ‘apt-get install rhino‘ YMMV.

  1. export CLASSPATH=/usr/share/java/js.jar
  2. java /path/to/some/javascript.js

Again, this will give some sort of return error code if it can’t parse it – but it’s not yet running through jslint… which is what we really want.

Firstly, download JSLint.js via (click on the ‘raw’ button)…

  1. (Requires CLASSPATH thing from above)
  2. java
  3. load(‘fulljslint.js’);
  4. to_test = readFile(‘/path/to/javascript/file/to/test.js’);
  5. result = JSLINT(to_test, null);

If ‘result’ is ‘false’ then you can inspect the errors via JSLINT.errors.

Next up, getting frontend-test-suite running, or something based upon it….

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