JSCoverage, implemented in JavaScript

npm install jscov@0.5.3


jscov Build Status

JSCoverage, implemented in JavaScript


npm install -g jscov


Start with jscov --help on the command line and the rest should be obvious.

You can also use it programmatically. It has two functions and can be used like this:

var jscov = require('jscov');

// Transforming source code
// Pass in some javascript code as a string and get a new string back,
// containing the same program but with code coverage support added.
// A filename has to be passed in as well, since the code coverage bits requires one.

var coveredSource = jscov.rewriteSource("var a = 1 + 2; console.log(a);", "myfilename.js");

// Transforming directories of code (like the command line client)
// This is simply the programmatic version of the command line client.
// Pass in a source directory and a target directory and all JavaScript (and CoffeeScript)
// found in source diriectory will be processed using `rewriteSource` and written to the target directory.
jscov.rewriteFolder("src", "src-cov", function(err) {
  // err will indicate if something went wrong.


Pull request are welcome obviously!

Running the tests requires jscoverage to be installed. This is because the main part of the tests compares the output of jscov to jscoverage. Get it here http://siliconforks.com/jscoverage or do what .travis.yml does to get it up and running.


  • Test using empty blocks in some different contexts. Are they removed?
  • Write a test for testing the actual code-coverage with and without using the expander
  • Attempt to instrument code that has already been instrumented (seems like jscoverage prevents that)
  • Branches current attempting to solve:
    • Float precision
    • Encodings
    • Octal-looking decimals
    • JS v1.6
  • Implement the following features from JSCoverage:
    • encoding
    • exclude
    • js-version
    • no-highlight
    • no-instrument
    • verbose
  • codeExpander should be tested to confirm that the program before and after does the exact same thing (could the AST's be reduced or should test programs be run?)
  • Look into the parse parameters "source" and "tokens"; might be helpful for simplying keeping source code and solivng the octal bug
  • Make jscoverage and jscov run with the same default parameters (for example encoding and js-version)