karma-regex-preprocessor

A karma preprocessor which does one or more regular expression substitutions on the file contents. It effectively just calls String.prototype.replace() with the parameters specified in the configuration.

Historically, the main motivation for this was that https://github.com/mode needed something to quickly simulate the nginx HttpSubModule.

Installation

Install from npm:

npm install karma-regex-preprocessor --save-dev

Configuration

Example configuration:

// karma.conf.js
module.exports = function(config) {
  config.set({
    preprocessors: {
      '**/*.js': ['regex']
    },
 
    regexPreprocessor: {
      rules: [
        {
          // Replacements for File1.
          fileName: "File1.js", replacement: [
            // Simple string replace of 'foo' with 'bar'.
            { replace: "foo", with: "bar" },
            // Prefix all numbers with '-'.
            { replace: /[\d]+/g, with: "-$1" },
            // Use a function to calculate replacement.
            { replace: "%rand%", with: function (match) { return Math.random() } }
          ]
        },
        {
          // Replacements for File2.
          fileName: "File2.js", replacement: [
            // Simple string replace of 'foo' with 'baz'.
            { replace: "foo", with: "baz" },
            // Prefix all numbers with '€'.
            { replace: /[\d]+/g, with: "€$1" },
            // Use a function to calculate replacement.
            { replace: "%rand%", with: function (match) { return Math.random()*5 } }
          ]
        }
      ]
    }
  });
};

License

The MIT License (MIT)