Checkstyle for javascript
JavaScript Emacs Lisp
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A command-line tool for analysing javascript source, providing measurements of function length, number of arguments, and cyclomatic complexity.

NOTE: jshint now does most of these checks, so you may not need this any more. Use jshint instead, it checks for a whole load of other things as well.


npm install jscheckstyle


jscheckstyle some-javascript.js some-other-javascript.js (default output as nice table on command line)
jscheckstyle --violations some-javascript.js (will output rule-violating functions only)
jscheckstyle --html some-javascript.js > output.html
jscheckstyle --json some-javascript.js > output.json
jscheckstyle --checkstyle some-javascript.js > output.xml (will output Java checkstyle-compatible output, useful for Jenkins)
jscheckstyle --emacs some-javascript.js (produces output suitable for Emacs flymake - see flymake-jschecksyle.el)


There are three rules at the moment which will be violated if:

  • function length is greater than 30 lines
  • number of arguments to a function is greater than 5
  • cyclomatic complexity for a function is greater than 10


To exclude certain directories or files from being checkstyled, simply create a .jscheckstyleignore file at current directory, and specify the directory or file name (relative to current directory) that you want to exclude.


It is possible to change the default rules by specifying different limits in comments before a function.

For example:

 * @jscheckstyle.functionLength=20
 * @jscheckstyle.numberOfArguments=10
 * @jscheckstyle.cyclomaticComplexity=30
function theFunction() {


Originally I started out modifying jsmeter to run as a command-line tool. Then I started hacking away, added some tests, the command-line interface, added the rules checking and the extra output types, replaced the parser with node-burrito and then realised there wasn't much of jsmeter left. So this tool is inspired by, and owes a huge debt to, jsmeter - but there's very little of the original code to be found (possibly only the HTML output renderer).