dependency-cruiser-fork/src/extract/utl/get-extension.js

Validate and visualize dependencies. With your rules. JavaScript, TypeScript, CoffeeScript. ES6, CommonJS, AMD.

const path = require("path");

/**
 * Returns the extension of the given file name path.
 *
 * Just using path.extname would be fine for most cases,
 * except for coffeescript, where a markdown extension can
 * mean literate coffeescript.
 *
 * @param {string} pFileName path to the file to be parsed
 * @return {string}          extension
 */
module.exports = (pFileName) => {
  let lReturnValue = path.extname(pFileName);

  if (lReturnValue === ".md") {
    return pFileName.endsWith(".coffee.md") ? ".coffee.md" : lReturnValue;
  }
  return lReturnValue;
};