vue-cli-plugin-coffee/index.js

const path = require("path");

module.exports = (API, projectOptions) => {
  API.chainWebpack((config) => {
    config.resolveLoader.modules.prepend(path.join(__dirname, "node_modules"));

    config.resolve.extensions.prepend(".coffee");

    if (!projectOptions.pages) {
      config.entry("app").clear().add("./src/main.coffee");
    }
    const coffeeRule = config.module
      .rule("coffee")
      .exclude(/node_modules|bower_components/)
      .test(/\.coffee$/);

    coffeeRule.use("cache-loader").loader(require.resolve("cache-loader"));

    if (process.env.NODE_ENV === "production" && !!projectOptions.parallel) {
      coffeeRule
        .use("thread-loader")
        .loader(require.resolve("thread-loader"))
        .options(
          typeof projectOptions.parallel === "number" ? { workers: projectOptions.parallel } : {},
        );
    }

    if (api.hasPlugin("babel")) {
      coffeeRule
        .use("babel-loader")
        .loader(require.resolve("babel-loader"))
        .options({
          presets: ["@babel/preset-env"],
        });
    }

    coffeeRule.use("coffee-loader").loader(require.resolve("coffee-loader"));
  });
};