rollup.config.js

import fs from 'fs';
import replace from 'rollup-plugin-replace';
import vue from 'rollup-plugin-vue';
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';

let banner = `
/** MIT licence */
/** https://github.com/bookingcom/powercalculator */
`;

export default {
  banner,
  input: 'src/index.js',
  plugins: [
    replace({
      'process.env.NODE_ENV': JSON.stringify( 'development' )
    }),
    resolve(),
    commonjs({
      include: ['node_modules/**'],
    }),
    vue({
      css (style, styles, compiler) {
          fs.writeFileSync('dist/powercalculator.css', styles.reduce((str, styleData) => {
            let { id, $compiled } = styleData,
              { code } = $compiled,
              relativeVuePath = id.replace(__dirname + '/src/', ''),
              codeTrimLineBreaks = code.replace(/[\n]+/g, '\n');

            str += `\n/* ${relativeVuePath} */\n${codeTrimLineBreaks}\n`;

            return str
          }, ''));
      }
    })
  ],
  output: {
    banner: banner,
    name: 'powercalculator',
    file: 'dist/powercalculator.js',
    format: 'umd',
    amd: {
      id: 'powercalculator'
    }
  }
}