@prantlf/karma-coffee-preprocessor

Karma preprocessor to compile CoffeeScript on the fly.

This is a fork of the original project with the following changes:

• Upgrade to CoffeeScript 2 (#87, #89, #91)
• Move coffeescript to peer dependencies
• Allow saving the transformed script with source map to disk
• Require Node.js 8 or newer

For more information on Karma see the homepage.

Installation

The easiest way is to keep @prantlf/karma-coffee-preprocessor as a devDependency. You can simply do it by:

npm install @prantlf/karma-coffee-preprocessor --save-dev

This package requires karma and coffeescript as peer dependencies. If your package manager doesn't install peer dependencies automatically, you will need to install them together:

npm install @prantlf/karma-coffee-preprocessor karma coffeescript --save-dev

Configuration

The following code shows the default configuration:

// karma.conf.js
module.exports = function(config) {
  config.set({
    preprocessors: {
      '**/*.coffee': ['coffee']
    },

    coffeePreprocessor: {
      // default options passed to the coffee compiler
      options: {
        bare: true,
        sourceMap: false
      },
      // default transforming the filenames
      transformPath(path) {
        return path.replace(/\.coffee$/, '.js')
      }
    },

    // make sure to include the .coffee files, not the compiled .js files
    files: [
      '**/*.coffee'
    ]
  })
}

If you set the sourceMap coffee compiler option to true then the generated source map will be inlined as a data URI.

Note that paths like **/*.coffee inside your preprocessors list will not match files where you are traversing up a directory (like ../app/*.coffee inside your files list) or where your basePath goes up a directory. If you need to match these, use something like preprocessors: { '../**/*.coffee': ['coffee'] }.

External Source Maps

If you use tools for analysing the web application or computing code coverage, you may need to save the preprocessed scripts with source maps to disk.

For example, the following configuration will save the transformed scripts and source maps as siblings of the original source files:

coffeePreprocessor: {
  options: {
    sourceMap: true
  },
  writeTransformed: true
},
files: [
  '*.coffee',
  { pattern: '*.map', included: false, nocache: true }
]

├── plus.coffee
├── plus.js
├── plus.js.map
├── test.coffee
├── test.js
└── test.js.map

For example, the following configuration will save the transformed scripts and source maps to a separate directory from the original source files:

coffeePreprocessor: {
  options: {
    sourceMap: true
  },
  writeTransformed: true,
  transformDir: 'tmp'
},
files: [
  '*.coffee',
  { pattern: '**/*.map', included: false, nocache: true }
]

├── plus.coffee
├── test.coffee
└── tmp
    ├── plus.js
    ├── plus.js.map
    ├── test.js
    └── test.js.map`

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Lint and test your code.

License

Copyright (C) 2011-2013 Google, Inc. Copyright (c) 2023 Ferdinand Prantl

Licensed under the MIT license.