Skip to content


Repository files navigation

Istanbul code coverage loader for Webpack

Cross-Platform Compatibility Build Status

Coverage Status Dependencies

npm License Buy us a tree

This is a Webpack loader that uses Istanbul to add code coverage instrumentation to your code. This is especially useful for in-browser testing, in a tool like Karma, where you can use karma-coverage-istanbul-reporter to output code coverage data in a variety of formats that are supported by services like Coveralls or Codacy.

Coverage Istanbul Loader is based on Istanbul Instrumenter Loader, but uses a newer version of the Istanbul API and has better support for source maps.


See the examples folder for usage examples for various use cases.


Contributions, enhancements, and bug-fixes are welcome! Open an issue on GitHub and submit a pull request.


To build/test the project locally on your computer:

  1. Clone this repo
    git clone

  2. Install dependencies
    npm install

  3. Build the code
    npm run build

  4. Run the tests
    npm test


coverage-istanbul-loader is 100% free and open-source, under the MIT license. Use it however you want.

This package is Treeware. If you use it in production, then we ask that you buy the world a tree to thank us for our work. By contributing to the Treeware forest you’ll be creating employment for local families and restoring wildlife habitats.

Big Thanks To

Thanks to these awesome companies for their support of Open Source developers ❤

Travis CI SauceLabs Coveralls